[1] ECHTERNKAMP K E, FEIST A, SCHAFER S et al. Ramsey-type phase control of free-electron beams[J]. Nature Physics, 12, 1000-1004(2016).

[2] MILLER R J D. Femtosecond crystallography with ultrabright electrons and X-rays： capturing chemistry in action[J]. Science, 343, 1108-1116(2014).

[3] ZEWAIL A H. Four-dimensional electron microscopy[J]. Science, 328, 187-193(2010).

[4] FRIGGE T, HAFKE B, WITTE T et al. Optically excited structural transition in atomic wires on surfaces at the quantum limit[J]. Nature, 544, 207-211(2017).

[5] KASMI L, KREIER D, BRADLER M et al. Femtosecond single-electron pulses generated by two-photon photoemission close to the work function[J]. New Journal of Physics, 17(2015).

[6] BORMANN R, STRAUCH S, SCHÄFER S et al. An ultrafast electron microscope gun driven by two-photon photoemission from a nanotip cathode[J]. Journal of Applied Physics, 118(2015).

[7] HOFFROGGE J, STEIN J P, KRUEGER M et al. Tip-based source of femtosecond electron pulses at 30 keV[J]. Journal of Applied Physics, 115(2014).

[8] CHATELAIN R P, MORRISON V R, KLARENAAR B L M et al. Coherent and incoherent electron-phonon coupling in graphite observed with radio-frequency compressed ultrafast electron diffraction[J]. Physical Review Letters, 113(2014).

[9] GLISERIN A, WALBRAN M, KRAUSZ F et al. Sub-phonon-period compression of electron pulses for atomic diffraction[J]. Nature Communications, 6, 8723(2015).

[10] MAXSON J, CESAR D, CALMASINI G et al. Direct measurement of sub-10 fs relativistic electron beams with ultralow emittance[J]. Physical Review Letters, 118, 154802(2017).

[11] TVAN OUDHEUSDEN, PASMANS P, GEER S BVAN DER et al. Compression of subrelativistic space-charge-dominated electron bunches for single-shot femtosecond electron diffraction[J]. Physical Review Letters, 105, 264801(2010).

[12] KEALHOFER C, SCHNEIDER W, EHBERGER D et al. All-optical control and metrology of electron pulses[J]. Science, 352, 429-433(2016).

[13] SEARS C M S, COLBY E, ISCHEBECK R et al. Production and characterization of attosecond electron bunch trains[J]. Physical Review Special Topics-Accelerators and Beams, 11(2008).

[14] KOZAK M, ECKSTEIN T, SCHONENBERGER N et al. Inelastic ponderomotive scattering of electrons at a high-intensity optical travelling wave in vacuum[J]. Nature Physics, 14, 121-125(2018).

[15] BAUM P, ZEWAIL A H. Attosecond electron pulses for 4D diffraction and microscopy[J]. Proceedings of the National Academy of Sciences of the United States of America, 104, 18409-18414(2007).

[16] MORIMOTO Y, BAUM P. Diffraction and microscopy with attosecond electron pulse trains[J]. Nature Physics, 14, 252-256(2018).

[17] KOZAK M, MCNEUR J, LEEDLE K J et al. Optical gating and streaking of free electrons with sub-optical cycle precision[J]. Nature Communications, 8, 14342(2017).

[18] PRIEBE K E, RATHJE C, YALUNIN S V et al. Attosecond electron pulse trains and quantum state reconstruction in ultrafast transmission electron microscopy[J]. Nature Photonics, 11, 793-797(2017).

[19] PLETTNER T, BYER R L, COLBY E et al. Visible-laser acceleration of relativistic electrons in a semi-infinite vacuum[J]. Physical Review Letters, 95, 134801(2005).

[20] COWAN B M. Two-dimensional photonic crystal accelerator structures[J]. Physical Review Special Topics-Accelerators and Beams, 6, 101301(2003).

[21] SCHäCHTER L, BYER R L, SIEMANN R H. Wake field in dielectric acceleration structures[J]. Physical Review E, 68(2003).

[22] PERALTA E A, SOONG K, ENGLAND R J et al. Demonstration of electron acceleration in a laser-driven dielectric microstructure[J]. Nature, 503, 91-94(2013).

[23] MICHALIK A M, SIPE J E. Evolution of non-gaussian electron bunches in ultrafast electron diffraction experiments： comparison to analytic model[J]. Journal of Applied Physics, 105(2009).

[24] OUDHEUSDEN T V, JONG E F D, GEER S B V D et al. Electron source concept for single-shot sub-100 fs electron diffraction in the 100 keV range[J]. Journal of Applied Physics, 102(2007).

[25] WILLIAMSON J C, CAO J, IHEE H et al. Clocking transient chemical changes by ultrafast electron diffraction[J]. Nature, 386, 159-162(1997).

[26] IHEE H, LOBASTOV V A, GOMEZ U M et al. Direct imaging of transient molecular structures with ultrafast diffraction[J]. Science, 291, 458-462(2001).

[27] CAO J, HAO Z, PARK H et al. Femtosecond electron diffraction for direct measurement of ultrafast atomic motions[J]. Applied Physics Letters, 83, 1044-1046(2003).

[28] SIWICK B J, DWYER J R, JORDAN R E et al. An atomic-level view of melting using femtosecond electron diffraction[J]. Science, 302, 1382-1385(2003).

[29] WALDECKER L, BERTONI R, ERNSTORFER R. Compact femtosecond electron diffractometer with 100 keV electron bunches approaching the single-electron pulse duration limit[J]. Journal of Applied Physics, 117(2015).

[30] CARBAJO S, NANNI E A, WONG L J et al. Direct longitudinal laser acceleration of electrons in free space[J]. Physical Review Accelerators and Beams, 19(2016).

[31] ZHU P, ZHU Y, HIDAKA Y et al. Femtosecond time-resolved Mev electron diffraction[J]. New Journal of Physics, 17(2015).

[32] ZHU P F, FU F C, LIU S G et al. Time-resolved visualization of laser-induced heating of gold with mev ultrafast electron diffraction[J]. Chinese Physics Letters, 31, 116101(2014).

[33] WEATHERSBY S P, BROWN G, CENTURION M et al. Mega-electron-volt ultrafast electron diffraction at slac national accelerator laboratory[J]. Review of Scientific Instruments, 86(2015).

[34] LI R, HUANG W, DU Y et al. Note： Single-shot continuously time-resolved MeV ultrafast electron diffraction[J]. Review of Scientific Instruments, 81(2010).

[35] YANG J, KAN K, NARUSE N et al. 100-femtosecond MeV electron source for ultrafast electron diffraction[J]. Radiation Physics and Chemistry, 78, 1106-1111(2009).

[36] HASTINGS J B, RUDAKOV F M, DOWELL D H et al. Ultrafast time-resolved electron diffraction with megavolt electron beams[J]. Applied Physics Letters, 89, 184109(2006).

[37] FILL E, VEISZ L, APOLONSKI A et al. Sub-fs electron pulses for ultrafast electron diffraction[J]. New Journal of Physics, 8, 272(2006).

[38] WANG X J, XIANG D, KIM T K et al. Potential of femtosecond electron diffraction using near-relativistic electrons from a photocathode RF electron gun[J]. Journal of the Korean Physical Society, 48, 390-396(2006).

[39] LAHME S, KEALHOFER C, KRAUSZ F et al. Femtosecond single-electron diffraction[J]. Structural Dynamics, 1(2014).

[40] AIDELSBURGER M, KIRCHNER F O, KRAUSZ F et al. Single-electron pulses for ultrafast diffraction[J]. Proceedings of the National Academy of Sciences of the United States of America, 107, 19714-19719(2010).

[41] WANG C, KANG Y. Double-mode electrostatic dispersing prism for electron pulse time-domain compression[J]. Optik, 125, 6352-6356(2014).

[42] GLISERIN A, APOLONSKI A, KRAUSZ F et al. Compression of single-electron pulses with a microwave cavity[J]. New Journal of Physics, 14(2012).

[43] GAO M, JEAN-RUEL H, COONEY R R et al. Full characterization of RF compressed femtosecond electron pulses using ponderomotive scattering[J]. Optics Express, 20, 12048-12058(2012).

[44] CHATELAIN R P, MORRISON V R, GODBOUT C et al. Ultrafast electron diffraction with radio-frequency compressed electron pulses[J]. Applied Physics Letters, 101(2012).

[45] TOKITA S, HASHIDA M, INOUE S et al. Single-shot ultrafast electron diffraction with a laser-accelerated sub-MeV electron pulse[J]. Physical Review Letters, 95, 111911(2009).

[46] BAUM P, ZEWAIL A H. 4D attosecond imaging with free electrons： diffraction methods and potential applications[J]. Chemical Physics, 366, 2-8(2009).

[47] BAUM P, ZEWAIL A. Femtosecond diffraction with chirped electron pulses[J]. Chemical Physics Letters, 462, 14-17(2008).

[48] KIRCHNER F O, GLISERIN A, KRAUSZ F et al. Laser streaking of free electrons at 25 keV[J]. Nature Photonics, 8, 52-57(2014).

[49] YANG J, GUEHR M, SHEN X et al. Diffractive imaging of coherent nuclear motion in isolated molecules[J]. Physical Review Letters, 117, 153002(2016).

[50] MORRISON V R, CHATELAIN R P, TIWARI K L et al. A photoinduced metal-like phase of monoclinic VO₂ revealed by ultrafast electron diffraction[J]. Science, 346, 445-448(2014).

[51] GAO M, LU C, JEAN-RUEL H et al. Mapping molecular motions leading to charge delocalization with ultrabright electrons[J]. Nature, 496, 343-346(2013).

[52] ERNSTORFER R, HARB M, HEBEISEN C T et al. The formation of warm dense matter： Experimental evidence for electronic bond hardening in gold[J]. Science, 323, 1033-1037(2009).

[53] HASSAN M T, BASKIN J S, LIAO B et al. High-temporal-resolution electron microscopy for imaging ultrafast electron dynamics[J]. Nature Photonics, 11, 425-430(2017).

[54] HASSAN M T, MOULET A et al. Optical attosecond pulses and tracking the nonlinear response of bound electrons[J]. Nature, 530, 66-70(2016).

[55] SHAO H C, STARACE A F. Detecting electron motion in atoms and molecules[J]. Physical Review Letters, 105, 263201(2010).

[56] YAKOVLEV V S, STOCKMAN M I, KRAUSZ F et al. Atomic-scale diffractive imaging of sub-cycle electron dynamics in condensed matter[J]. Scientific Reports, 5, 14581(2015).

[57] VANACORE G M, FITZPATRICK A W P, ZEWAIL A H. Four-dimensional electron microscopy： ultrafast imaging， diffraction and spectroscopy in materials science and biology[J]. Nano Today, 11, 228-249(2016).

[58] CHASE T, TRIGO M, REID A H et al. Ultrafast electron diffraction from non-equilibrium phonons in femtosecond laser heated Au films[J]. Applied Physics Letters, 108(2016).

[59] FITZPATRICK A W P, VANACORE G M, ZEWAIL A H. Nanomechanics and intermolecular forces of amyloid revealed by four-dimensional electron microscopy[J]. Proceedings of the National Academy of Sciences of the United States of America, 112, 3380-3385(2015).

[60] ZEWAIL A H. 4D visualization of matter：Recent collected works of Ahmed H Zewail， Nobel Laureate[C](2014).

[61] SCIAINI G, MILLER R J D. Femtosecond electron diffraction： Heralding the era of atomically resolved dynamics[J]. Reports on Progress in Physics, 74(2011).

[62] MILLER R J D, ERNSTORFER R, HARB M et al. 'Making the molecular movie'： First frames[J]. Acta Crystallographica a-Foundation and Advances, 66, 137-156(2010).

[63] ZEWAIL A H, THOMAS J M[M]. 4D ultrafast electron imaging： developments and applications, 179-273(2010).

[64] ZEWAIL A H. 4D ultrafast electron diffraction， crystallography， and microscopy[J]. Annual Review of Physical Chemistry, 57, 65-103(2006).

[65] REED B W. Femtosecond electron pulse propagation for ultrafast electron diffraction[J]. Journal of Applied Physics, 100(2006).

[66] SIWICK B J, DWYER J R, JORDAN R E et al. Femtosecond electron diffraction studies of strongly driven structural phase transitions[J]. Chemical Physics, 299, 285-305(2004).

[67] HEBEISEN C T, SCIAINI G, HARB M et al. Grating enhanced ponderomotive scattering for visualization and full characterization of femtosecond electron pulses[J]. Optics Express, 16, 3334-3341(2008).

[68] EICHBERGER M, SCHAEFER H, KRUMOVA M et al. Snapshots of cooperative atomic motions in the optical suppression of charge density waves[J]. Nature, 468, 799-802(2010).

[69] BAUM P, YANG D S, ZEWAIL A H. 4D visualization of transitional structures in phase transformations by electron diffraction[J]. Science, 318, 788-792(2007).

[70] PARK H, WANG X, NIE S et al. Direct and real-time probing of both coherent and thermal lattice motions[J]. Solid State Communications, 136, 559-563(2005).

[71] MUSUMECI P, MOODY J T, SCOBY C M et al. Laser-induced melting of a single crystal gold sample by time-resolved ultrafast relativistic electron diffraction[J]. Applied Physics Letters, 97(2010).

[72] FU F, LIU S, ZHU P et al. High quality single shot ultrafast MeV electron diffraction from a photocathode radio-frequency gun[J]. Review of Scientific Instruments, 85(2014).

[73] GIRET Y, NARUSE N, DARASZEWICZ S L et al. Determination of transient atomic structure of laser-excited materials from time-resolved diffraction data[J]. Applied Physics Letters, 103, 253107(2013).

[74] MILLER R J D. Mapping atomic motions with ultrabright electrons： the chemists' gedanken experiment enters the lab frame[J]. Annual Review of Physical Chemistry, 65, 583-604(2014).

[75] SCHäCHTER L, KIMURA W D, BEN-ZVI I. Ultrashort microbunch electron source[J]. AIP Conference Proceedings, 1777(2016).

[76] YANAGISAWA H, HAFNER C, DONA P et al. Laser-induced field emission from a tungsten tip： Optical control of emission sites and the emission process[J]. Physical Review B, 81, 115429(2010).

[77] HOMMELHOFF P, SORTAIS Y, AGHAJANI-TALESH A et al. Field emission tip as a nanometer source of free electron femtosecond pulses[J]. Physical Review Letters, 96(2006).

[78] NEIDERT R E, PHILLIPS P M, SMITH S T et al. Field emission triodes[J]. IEEE Transactions on Electron Devices, 38, 661-665(1991).

[79] BARWICK B, PARK H S, KWON O H et al. 4D imaging of transient structures and morphologies in ultrafast electron microscopy[J]. Science, 322, 1227-1231(2008).

[80] HOMMELHOFF P, KEALHOFER C, KASEVICH M A. Reaching the resolved tunnel regime for a femtosecond oscillator driven field emission electron source[J]. Laser Physics, 19, 736-738(2009).

[81] ROPERS C, SOLLI D R, SCHULZ C P et al. Localized multiphoton emission of femtosecond electron pulses from metal nanotips[J]. Physical Review Letters, 98(2007).

[82] ROPERS C, ELSAESSER T, CERULLO G et al. Ultrafast optical excitations of metallic nanostructures： From light confinement to a novel electron source[J]. New Journal of Physics, 9, 397(2007).

[83] BARWICK B, CORDER C, STROHABER J et al. Laser-induced ultrafast electron emission from a field emission tip[J]. New Journal of Physics, 9, 142(2007).

[84] HOMMELHOFF P, KEALHOFER C, KASEVICH M A. Ultrafast electron pulses from a tungsten tip triggered by low-power femtosecond laser pulses[J]. Physical Review Letters, 97, 247402(2006).

[85] BARWICK B, FLANNIGAN D J, ZEWAIL A H. Photon-induced near-field electron microscopy[J]. Nature, 462, 902-906(2009).

[86] CARBONE F, KWON O H, ZEWAIL A H. Dynamics of chemical bonding mapped by energy-resolved 4D electron microscopy[J]. Science, 325, 181-184(2009).

[87] LOBASTOV V A, SRINIVASAN R, ZEWAIL A H. Four-dimensional ultrafast electron microscopy[J]. Proceedings of the National Academy of Sciences of the United States of America, 102, 7069-7073(2005).

[88] AESCHLIMANN M, HULL E, CAO J et al. A picosecond electron gun for surface analysis[J]. Review of Scientific Instruments, 66, 1000-1009(1995).

[89] BANFI F, GIANNETTI C, FERRINI G et al. Experimental evidence of above-threshold photoemission in solids[J]. Physical Review Letters, 94(2005).

[90] ZEITLER B, FLOETTMANN K, GRüNER F. Linearization of the longitudinal phase space without higher harmonic field[J]. Physical Review Special Topics-Accelerators and Beams, 18, 120102(2015).

[91] BUCK A, NICOLAI M, SCHMID K et al. Real-time observation of laser-driven electron acceleration[J]. Nature Physics, 7, 543(2011).

[92] LUNDH O, RECHATIN C et al. Few femtosecond， few kiloampere electron bunch produced by a laser-plasma accelerator[J]. Nature Physics, 7, 219-222(2011).

[93] ESAREY E, SCHROEDER C B, LEEMANS W P. Physics of laser-driven plasma-based electron accelerators[J]. Reviews of Modern Physics, 81, 1229-1285(2009).

[94] ENGLAND R J, NOBLE R J, BANE K et al. Dielectric laser accelerators[J]. Reviews of Modern Physics, 86, 1337-1389(2014).

[95] CHEN Min, LIU Feng, LI Boyuan等. Development and prospect of laser plasma wakefield accelerator[J]. High Power Laser and Particle Beams, 32(2020).

[96] PERRY M D, MOUROU G. Terawatt to petawatt subpicosecond lasers[J]. Science, 264, 917-924(1994).

[97] STRICKLAND D, MOUROU G. Compression of amplified chirped optical pulses[J]. Optics Communications, 56, 219-221(1985).

[98] MANGLES S P, MURPHY C D, NAJMUDIN Z et al. Monoenergetic beams of relativistic electrons from intense laser-plasma interactions[J]. Nature, 431, 535-538(2004).

[99] GEDDES C G R, TOTH C, JVAN TILBORG et al. High-quality electron beams from a laser wakefield accelerator using plasma-channel guiding[J]. Nature, 431, 538-541(2004).

[100] FAURE J, GLINEC Y, PUKHOV A et al. A laser-plasma accelerator producing monoenergetic electron beams[J]. Nature, 431, 541-544(2004).

[101] GONSALVES A J, NAKAMURA K, DANIELS J et al. Petawatt laser guiding and electron beam acceleration to 8 GeV in a laser-heated capillary discharge waveguide[J]. Physical Review Letters, 122(2019).

[102] LEEMANS W P, GONSALVES A J, MAO H S et al. Multi-GeV electron beams from capillary-discharge-guided subpetawatt laser pulses in the self-trapping regime[J]. Physical Review Letters, 113, 245002(2014).

[103] KNEIP S, NAGEL S R, MARTINS S F et al. Near-GeV acceleration of electrons by a nonlinear plasma wave driven by a self-guided laser pulse[J]. Physical Review Letters, 103(2009).

[104] HAFZ N A M, JEONG T M, CHOI I W et al. Stable generation of GeV-class electron beams from self-guided laser-plasma channels[J]. Nature Photonics, 2, 571-577(2008).

[105] LEEMANS W P, NAGLER B, GONSALVES A J et al. GeV electron beams from a centimetre-scale accelerator[J]. Nature Physics, 2, 696-699(2006).

[106] GUéNOT D, GUSTAS D, VERNIER A et al. Relativistic electron beams driven by kHz single-cycle light pulses[J]. Nature Photonics, 11, 293-296(2017).

[107] SCHMID K. Few-cycle laser-driven electron acceleration[J]. Physical Review Letters, 102, 124801(2009).

[108] TOOLEY M P, ERSFELD B, YOFFE S R et al. Towards attosecond high-energy electron bunches： controlling self-injection in laser-wakefield accelerators through plasma-density modulation[J]. Physical Review Letters, 119(2017).

[109] HORN V, PETRíLKA V, KRUS M. Short electron bunches from injection by perpendicularly crossing pulses[J]. Plasma Physics and Controlled Fusion, 61(2019).

[110] ZHAO Q, WENG S M, CHEN M et al. Sub-femtosecond electron bunches in laser wakefield acceleration via injection suppression with a magnetic field[J]. Plasma Physics and Controlled Fusion, 61(2019).

[111] SCHUMAKER W, NAKANII N, MCGUFFEY C et al. Ultrafast electron radiography of magnetic fields in high-intensity laser-solid interactions[J]. Physical Review Letters, 110(2013).

[112] ZHANG C J, HUA J F, WAN Y et al. Femtosecond probing of plasma wakefields and observation of the plasma wake reversal using a relativistic electron bunch[J]. Physical Review Letters, 119(2017).

[113] ROUSSE A. Production of a keV X-ray beam from synchrotron radiation in relativistic laser-plasma interaction[J]. Physical Review Letters, 93, 135005(2004).

[114] ESAREY E, SHADWICK B A, CATRAVAS P et al. Synchrotron radiation from electron beams in plasma-focusing channels[J]. Physical Review E, 65(2002).

[115] SHAH R C, ALBERT F, PHUOC KTA et al. Coherence-based transverse measurement of synchrotron X-ray radiation from relativistic laser-plasma interaction and laser-accelerated electrons[J]. Physical Review E, 74(2006).

[116] KNEIP S, MCGUFFEY C, MARTINS J L et al. Bright spatially coherent synchrotron X-rays from a table-top source[J]. Nature Physics, 6, 980-983(2010).

[117] KNEIP S, MCGUFFEY C, DOLLAR F et al. X-ray phase contrast imaging of biological specimens with femtosecond pulses of betatron radiation from a compact laser plasma wakefield accelerator[J]. Applied Physics Letters, 99(2011).

[118] FOURMAUX S, CORDE S, PHUOC K T et al. Single shot phase contrast imaging using laser-produced betatron X-ray beams[J]. Optics Letters, 36, 2426-2428(2011).

[119] COLE J M, SYMES D R, LOPES N C et al. High-resolution μCT of a mouse embryo using a compact laser-driven X-ray betatron source[J]. Proceedings of the National Academy of Sciences of the United States of America, 115, 6335-6340(2018).

[120] WENZ J, SCHLEEDE S, KHRENNIKOV K et al. Quantitative X-ray phase-contrast microtomography from a compact laser-driven betatron source[J]. Nature Communications, 6, 7568(2015).

[121] MAHIEU B, JOURDAIN N, PHUOC KTA et al. Probing warm dense matter using femtosecond X-ray absorption spectroscopy with a laser-produced betatron source[J]. Nature Communications, 9, 3276(2018).

[122] KODAMA R, SENTOKU Y, CHEN Z L et al. Plasma devices to guide and collimate a high density of MeV electrons[J]. Nature, 432, 1005-1008(2004).

[123] NAKAJIMA H, TOKITA S, INOUE S et al. Divergence-free transport of laser-produced fast electrons along a meter-long wire target[J]. Physical Review Letters, 110, 155001(2013).

[124] WANG W, LIU J, CAI Y et al. Angular and energy distribution of fast electrons emitted from a solid surface irradiated by femtosecond laser pulses in various conditions[J]. Physics of Plasmas, 17(2010).

[125] HU G Y, LEI A L, WANG W T et al. Collimated hot electron jets generated from subwavelength grating targets irradiated by intense short-pulse laser[J]. Physics of Plasmas, 17(2010).

[126] BRANDL F, HIDDING B, OSTERHOLZ J et al. Directed acceleration of electrons from a solid surface by sub-10-fs laser pulses[J]. Physical Review Letters, 102, 195001(2009).

[127] LI Y T, YUAN X H, XU M H et al. Observation of a fast electron beam emitted along the surface of a target irradiated by intense femtosecond laser pulses[J]. Physical Review Letters, 96, 165003(2006).

[128] GULDE M, SCHWEDA S, STORECK G et al. Ultrafast low-energy electron diffraction in transmission resolves polymer/graphene superstructure dynamics[J]. Science, 345, 200-204(2014).

[129] QUINONEZ E, HANDALI J, BARWICK B. Femtosecond photoelectron point projection microscope[J]. Review of Scientific Instruments, 84, 103710(2013).

[130] KEALHOFER C, FOREMAN S M, GERLICH S et al. Ultrafast laser-triggered emission from hafnium carbide tips[J]. Physical Review B, 86(2012).

[131] HERINK G, SOLLI D R, GULDE M et al. Field-driven photoemission from nanostructures quenches the quiver motion[J]. Nature, 483, 190-193(2012).

[132] KRüGER M, SCHENK M, HOMMELHOFF P. Attosecond control of electrons emitted from a nanoscale metal tip[J]. Nature, 475, 78-81(2011).

[133] BORMANN R, GULDE M, WEISMANN A et al. Tip-enhanced strong-field photoemission[J]. Physical Review Letters, 105, 147601(2010).

[134] SCHENK M, KRüGER M, HOMMELHOFF P. Strong-field above-threshold photoemission from sharp metal tips[J]. Physical Review Letters, 105, 257601(2010).

[135] YANAGISAWA H, HAFNER C, DONá P et al. Optical control of field-emission sites by femtosecond laser pulses[J]. Physical Review Letters, 103, 257603(2009).

[136] EHBERGER D, HAMMER J, EISELE M et al. Highly coherent electron beam from a laser-triggered tungsten needle tip[J]. Physical Review Letters, 114, 227601(2015).

[137] FEIST A, BACH N, RUBIANO D A SILVA N et al. Ultrafast transmission electron microscopy using a laser-driven field emitter： Femtosecond resolution with a high coherence electron beam[J]. Ultramicroscopy, 176, 63-73(2017).

[138] YANG D S, MOHAMMED O F, ZEWAIL A H. Scanning ultrafast electron microscopy[J]. Proceedings of the National Academy of Sciences of the United States of America, 107, 14993-14998(2010).

[139] COOK B, BRONSGEEST M, HAGEN K et al. Improving the energy spread and brightness of thermal-field （Schottky） emitters with PHAST-photo assisted Schottky tip[J]. Ultramicroscopy, 109, 403-412(2009).

[140] FURSEY G. Field emission in vacuum microelectronics[M]. Microdevices(2005).

[141] ICHIMURA T, SHIMIZU R et al. Quantitative evaluation of spatial coherence of the electron beam from low temperature field emitters[J]. Physical Review Letters, 92, 246103(2004).

[142] NAGAOKA K, YAMASHITA T, UCHIYAMA S et al. Monochromatic electron emission from the macroscopic quantum state of a superconductor[J]. Nature, 396, 557-559(1998).

[143] MCCULLOCH A J, SHELUDKO D V, JUNKER M et al. High-coherence picosecond electron bunches from cold atoms[J]. Nature Communications, 4, 1692(2013).

[144] ENGELEN W J, HEIJDEN M AVAN DER, BAKKER D J et al. High-coherence electron bunches produced by femtosecond photoionization[J]. Nature Communications, 4, 1693(2013).

[145] GEER S BVAN DER, DE LOOS M J, VREDENBREGT E J D et al. Ultracold electron source for single-shot， ultrafast electron diffraction[J]. Microscopy and Microanalysis, 15, 282-289(2009).

[146] LUITEN O J, CLAESSENS B J, GEER S BVAN DER et al. Ultracold electron sources[J]. International Journal of Modern Physics A, 22, 3882-3897(2007).

[147] CLAESSENS B J, GEER S BVAN DER, TABAN G et al. Ultracold electron source[J]. Physical Review Letters, 95, 164801(2005).

[148] METCALFHAROLD J., STRATEN P V D. Laser cooling and trapping[M]. Graduate texts in contemporary physics(1999).

[149] ENGELEN W J, SMAKMAN E P, BAKKER D J et al. Effective temperature of an ultracold electron source based on near-threshold photoionization[J]. Ultramicroscopy, 136, 73-80(2014).

[150] TABAN G, REIJNDERS M P, FLESKENS B et al. Ultracold electron source for single-shot diffraction studies[J]. EPL, 91, 46004(2010).

[151] SALIBA S D, PUTKUNZ C T, SHELUDKO D V et al. Spatial coherence of electron bunches extracted from an arbitrarily shaped cold atom electron source[J]. Optics Express, 20, 3967-3974(2012).

[152] MOURIK M W V, ENGELEN W J, VREDENBREGT E J D et al. Ultrafast electron diffraction using an ultracold source[J]. Structural Dynamics, 1(2014).

[153] SPEIRS R W, PUTKUNZ C T, MCCULLOCH A J et al. Single-shot electron diffraction using a cold atom electron source[J]. Journal of Physics B-Atomic Molecular and Optical Physics, 48, 214002(2015).

[154] WIMMER L, HERINK G, SOLLI D R et al. Terahertz control of nanotip photoemission[J]. Nature Physics, 10, 432-436(2014).

[155] FEIST A, ECHTERNKAMP K E, SCHAUSS J et al. Quantum coherent optical phase modulation in an ultrafast transmission electron microscope[J]. Nature, 521, 200-203(2015).

[156] FLANNIGAN D J, ZEWAIL A H. 4D electron microscopy： Principles and applications[J]. Accounts of Chemical Research, 45, 1828-1839(2012).

[157] MORIMOTO Y, BAUM P. Attosecond control of electron beams at dielectric and absorbing membranes[J]. Physical Review A, 97(2018).

[158] HILBERT S A, UITERWAAL C, BARWICK B et al. Temporal lenses for attosecond and femtosecond electron pulses[J]. Proceedings of the National Academy of Sciences of the United States of America, 106, 10558-10563(2009).

[159] FERRARIO M, ALESINI D, BACCI A et al. Experimental demonstration of emittance compensation with velocity bunching[J]. Physical Review Letters, 104(2010).

[160] ANDERSON S G, MUSUMECI P, ROSENZWEIG J B et al. Velocity bunching of high-brightness electron beams[J]. Physical Review Special Topics-Accelerators and Beams, 8(2005).

[161] LU X H, TANG C X, LI R K et al. Generation and measurement of velocity bunched ultrashort bunch of pC charge[J]. Physical Review Special Topics-Accelerators and Beams, 18(2015).

[162] GAHLMANN A, PARK S T, ZEWAIL A H. Ultrashort electron pulses for diffraction， crystallography and microscopy： theoretical and experimental resolutions[J]. Physical Chemistry Chemical Physics, 10, 2894-2909(2008).

[163] SIWICK B J, DWYER J R, JORDAN R E et al. Ultrafast electron optics： propagation dynamics of femtosecond electron packets[J]. Journal of Applied Physics, 92, 1643-1648(2002).

[164] SCOBY C M, LI R K, THRELKELD E et al. Single-shot 35 fs temporal resolution electron shadowgraphy[J]. Applied Physics Letters, 102(2013).

[165] KASSIER G H, ERASMUS N, HAUPT K et al. Photo-triggered pulsed cavity compressor for bright electron bunches in ultrafast electron diffraction[J]. Applied Physics B-Lasers and Optics, 109, 249-257(2012).

[166] KASSIER G H, HAUPT K, ERASMUS N et al. Achromatic reflectron compressor design for bright pulses in femtosecond electron diffraction[J]. Journal of Applied Physics, 105, 113111(2009).

[167] MICHALIK A M, SHERMAN E Y, SIPE J E. Theory of ultrafast electron diffraction： the role of the electron bunch properties[J]. Journal of Applied Physics, 104(2008).

[168] ROSENZWEIG J B[M]. Fundamentals of beam physics(2003).

[169] LUITEN O J, GEER S BVAN DER, DE LOOS M J et al. How to realize uniform three-dimensional ellipsoidal electron bunches[J]. Physical Review Letters, 93(2004).

[170] ZANDI O, WILKIN K J, XIONG Y et al. High current table-top setup for femtosecond gas electron diffraction[J]. Structural Dynamics, 4(2017).

[171] WALBRAN M, GLISERIN A, JUNG K et al. 5-femtosecond laser-electron synchronization for pump-probe crystallography and diffraction[J]. Physical Review Applied, 4(2015).

[172] SCHULZ S, GRGURAŠ I, BEHRENS C et al. Femtosecond all-optical synchronization of an X-ray free-electron laser[J]. Nature Communications, 6, 5938(2015).

[173] BRUSSAARD G J H, LASSISE A, PASMANS P L E M et al. Direct measurement of synchronization between femtosecond laser pulses and a 3 GHz radio frequency electric field inside a resonant cavity[J]. Applied Physics Letters, 103, 141105(2013).

[174] ZHANG D, FALLAHI A, HEMMER M et al. Segmented terahertz electron accelerator and manipulator （STEAM）[J]. Nature Photonics, 12, 336-342(2018).

[175] NANNI E A, HUANG W R, HONG K H et al. Terahertz-driven linear electron acceleration[J]. Nature Communications, 6, 8486(2015).

[176] EHBERGER D, RYABOV A, BAUM P. Tilted electron pulses[J]. Physical Review Letters, 121(2018).

[177] LI R K, HOFFMANN M C, NANNI E A et al. Terahertz-based subfemtosecond metrology of relativistic electron beams[J]. Physical Review Accelerators and Beams, 22(2019).

[178] CURRY E, FABBRI S, MAXSON J et al. Meter-scale terahertz-driven acceleration of a relativistic beam[J]. Physical Review Letters, 120(2018).

[179] ZHAO L, WANG Z, LU C et al. Terahertz streaking of few-femtosecond relativistic electron beams[J]. Physical Review X, 8(2018).

[180] OUDHEUSDEN T V, PASMANS P L E M, GEER S B V D et al. Compression of sub-relativistic space-charge-dominated electron bunches for single-shot femtosecond electron diffraction[J]. Physical Review Letters, 105, 264801(2010).

[181] EHBERGER D, MOHLER K J, VASILEIADIS T et al. Terahertz compression of electron pulses at a planar mirror membrane[J]. Physical Review Applied, 11(2019).

[182] OTTO M R, COTRET L P R D, STERN M J et al. Solving the jitter problem in microwave compressed ultrafast electron diffraction instruments： Robust sub-50 fs cavity-laser phase stabilization[J]. Structural Dynamics, 4(2017).

[183] BREUER J, HOMMELHOFF P. Laser-based acceleration of nonrelativistic electrons at a dielectric structure[J]. Physical Review Letters, 111, 134803(2013).

[184] MORIMOTO Y, BAUM P. Single-cycle optical control of beam electrons[J]. Physical Review Letters, 125, 193202(2020).

[185] KOZAK M, SCHOENENBERGER N, HOMMELHOFF P. Ponderomotive generation and detection of attosecond free-electron pulse trains[J]. Physical Review Letters, 120, 103203(2018).

[186] BANERJEE S, SEPKE S, SHAH R et al. Optical deflection and temporal characterization of an ultrafast laser-produced electron beam[J]. Physical Review Letters, 95(2005).

[187] LIU Y, ZHANG J, WU H et al. Ponderomotive scattering of electrons and its application to measure the pulse duration of ultrafast electron beams[J]. Journal of Applied Physics, 103(2008).

[188] HEBEISEN C T, ERNSTORFER R, HARB M et al. Femtosecond electron pulse characterization using laser ponderomotive scattering[J]. Optics Letters, 31, 3517-3519(2006).

[189] FABIAŃSKA J, KASSIER G, FEURER T. Split ring resonator based THz-driven electron streak camera featuring femtosecond resolution[J]. Scientific Reports, 4, 5645(2014).

[190] BAUM P, ZEWAIL A H. Breaking resolution limits in ultrafast electron diffraction and microscopy[J]. Proceedings of the National Academy of Sciences of the United States of America, 103, 16105-16110(2006).

[191] ZHOU C, BAI Y, SONG L et al. Direct mapping of attosecond electron dynamics[J]. Nature Photonics, 15, 216-221(2021).

[192] PARK S T, LIN M, ZEWAIL A H. Photon-induced near-field electron microscopy （PINEM）： theoretical and experimental[J]. New Journal of Physics, 12, 123028(2010).

[193] YURTSEVER A, VEEN R MVAN DER, ZEWAIL A H. Subparticle ultrafast spectrum imaging in 4D electron microscopy[J]. Science, 335, 59-64(2012).

[194] PIAZZA L, LUMMEN T T A, QUINONEZ E et al. Simultaneous observation of the quantization and the interference pattern of a plasmonic near-field[J]. Nature Communications, 6, 6407(2015).

[195] FU X, BARANTANI F, GARGIULO S et al. Nanoscale-femtosecond dielectric response of mott insulators captured by two-color near-field ultrafast electron microscopy[J]. Nature Communications, 11, 5770-5770(2020).

[196] PARK S T, ZEWAIL A H. Chirped imaging pulses in four-dimensional electron microscopy： femtosecond pulsed hole burning[J]. New Journal of Physics, 14(2012).

[197] PLEMMONS D A, STAE PARK, ZEWAIL A H et al. Characterization of fast photoelectron packets in weak and strong laser fields in ultrafast electron microscopy[J]. Ultramicroscopy, 146, 97-102(2014).

[198] STORECK G, HORSTMANN J G, DIEKMANN T et al. Structural dynamics of incommensurate charge-density waves tracked by ultrafast low-energy electron diffraction[J]. Structural Dynamics, 7(2020).

[199] HORSTMANN J G, BöCKMANN H et al. Coherent control of a surface structural phase transition[J]. Nature, 583, 232-236(2020).

[200] QI F, MA Z, ZHAO L et al. Breaking 50 femtosecond resolution barrier in MeV ultrafast electron diffraction with a double bend achromat compressor[J]. Physical Review Letters, 124, 134803(2020).

[201] YANG J, ZHU X, PF. NUNES J et al. Simultaneous observation of nuclear and electronic dynamics by ultrafast electron diffraction[J]. Science, 368, 885-889(2020).

[202] KOGAR A, ZONG A, DOLGIREV P E et al. Light-induced charge density wave in LaTe₃[J]. Nature Physics, 16, 159-163(2020).

[203] NYBY C M, PEMMARAJU C D et al. An ultrafast symmetry switch in a weyl semimetal[J]. Nature, 565, 61-66(2019).

[204] [webpage]. http：//www.physics.mcgill.ca/siwicklab/hardware.html

[205] CARBONE F, YANG D S, GIANNINI E et al. Direct role of structural dynamics in electron-lattice coupling of superconducting cuprates[J]. Proceedings of the National Academy of Sciences of the United States of America, 105, 20161-20166(2008).

[206] RUAN C Y, LOBASTOV V A, VIGLIOTTI F et al. Ultrafast electron crystallography of interfacial water[J]. Science, 304, 80-84(2004).

[207] CHEN S, SEIDEL M T, ZEWAIL A H. Atomic-scale dynamical structures of fatty acid bilayers observed by ultrafast electron crystallography[J]. Proceedings of the National Academy of Sciences of the United States of America, 102, 8854-8859(2005).

[208] DE COTRET L P R, POHLS J H, STERN M J et al. Time- and momentum-resolved phonon population dynamics with ultrafast electron diffuse scattering[J]. Physical Review B, 100, 214115(2019).

[209] PARK H S, BASKIN J S et al. Atomic-scale imaging in real and energy space developed in ultrafast electron microscopy[J]. Nano Letters, 7, 2545-2551(2007).

[210] PARK H S, BASKIN J S, BARWICK B et al. 4D ultrafast electron microscopy： Imaging of atomic motions， acoustic resonances， and moire fringe dynamics[J]. Ultramicroscopy, 110, 7-19(2009).

[211] YURTSEVER A, ZEWAIL A H. 4D nanoscale diffraction observed by convergent-beam ultrafast electron microscopy[J]. Science, 326, 708-712(2009).

[212] KWON O H, BARWICK B, PARK H S et al. 4D visualization of embryonic， structural crystallization by single-pulse microscopy[J]. Proceedings of the National Academy of Sciences of the United States of America, 105, 8519-8524(2008).

[213] KWON O H, ZEWAIL A H. 4D electron tomography[J]. Science, 328, 1668-1673(2010).

[214] CREMONS D R, PLEMMONS D A, FLANNIGAN D J. Defect-mediated phonon dynamics in TaS₂ and WSe₂[J]. Structural Dynamics, 4(2017).

[215] ZHANG Y, FLANNIGAN D J. Observation of anisotropic strain-wave dynamics and few-layer dephasing in MoS₂ with ultrafast electron microscopy[J]. Nano Letters, 19, 8216-8224(2019).

[216] ZHANG M, CAO G, TIAN H et al. Picosecond view of a martensitic transition and nucleation in the shape memory alloy Mn₅₀Ni₄₀Sn₁₀ by four-dimensional transmission electron microscopy[J]. Physical Review B, 96, 174203(2017).

[217] RYABOV A, BAUM P. Electron microscopy of electromagnetic waveforms[J]. Science, 353, 374-377(2016).

[218] LORENZ U J, ZEWAIL A H. Observing liquid flow in nanotubes by 4D electron microscopy[J]. Science, 344, 1496-1500(2014).

[219] CHEN B, FU X, TANG J et al. Dynamics and control of gold-encapped gallium arsenide nanowires imaged by 4D electron microscopy[J]. Proceedings of the National Academy of Sciences of the United States of America, 114, 12876-12881(2017).

[220] FU X, LIU S, CHEN B et al. Observation and control of unidirectional ballistic dynamics of nanoparticles at a liquid-gas interface by 4D electron microscopy[J]. ACS Nano, 15, 6801-6810(2021).

[221] DANZ T, DOMRÖSE T, ROPERS C. Ultrafast nanoimaging of the order parameter in a structural phase transition[J]. Science, 371, 371-374(2021).

[222] LUMMEN T T A, LAMB R J, BERRUTO G et al. Imaging and controlling plasmonic interference fields at buried interfaces[J]. Nature Communications, 7, 13156(2016).

[223] WANG K, DAHAN R, SHENTCIS M et al. Coherent interaction between free electrons and a photonic cavity[J]. Nature, 582, 50-54(2020).

[224] KFIR O, LOURENÇO-MARTINS H, STORECK G et al. Controlling free electrons with optical whispering-gallery modes[J]. Nature, 582, 46-49(2020).

[225] VANACORE G M, BERRUTO G, MADAN I et al. Ultrafast generation and control of an electron vortex beam via chiral plasmonic near fields[J]. Nature Materials, 18, 573-579(2019).

[226] SILVA N RDA, MOELLER M, FEIST A et al. Nanoscale mapping of ultrafast magnetization dynamics with femtosecond lorentz microscopy[J]. Physical Review X, 8(2018).

[227] FU X, POLLARD S D, CHEN B et al. Optical manipulation of magnetic vortices visualized in situ by lorentz electron microscopy[J]. Science Advances, 4(2018).

[228] CAO G, JIANG S, AKERMAN J et al. Femtosecond laser driven precessing magnetic gratings[J]. Nanoscale, 13, 3746-3756(2021).

[229] FITZPATRICK A W P, LORENZ U J, VANACORE G M et al. 4D cryo-electron microscopy of proteins[J]. Journal of the American Chemical Society, 135, 19123-19126(2013).

[230] LORENZ U J, ZEWAIL A H. Biomechanics of DNA structures visualized by 4D electron microscopy[J]. Proceedings of the National Academy of Sciences of the United States of America, 110, 2822-2827(2013).

[231] FU X, CHEN B, TANG J et al. Imaging rotational dynamics of nanoparticles in liquid by 4D electron microscopy[J]. Science, 355, 494-498(2017).

[232] FU X, CHEN B, TANG J et al. Photoinduced nanobubble-driven superfast diffusion of nanoparticles imaged by 4D electron microscopy[J]. Science Advances, 3(2017).

[233] FU X, CHEN B, LI C et al. Direct visualization of photomorphic reaction dynamics of plasmonic nanoparticles in liquid by four-dimensional electron microscopy[J]. Journal of Physical Chemistry Letters, 9, 4045-4052(2018).

[234] JING C, ZHU Y, LIU A et al. Tunable electron beam pulser for picoseconds stroboscopic microscopy in transmission electron microscopes[J]. Ultramicroscopy, 207, 112829(2019).

[235] SCHLIEP K B, KATZ M B et al. Laser-free GHz stroboscopic transmission electron microscope： Components， system integration， and practical considerations for pump-probe measurements[J]. Review of Scientific Instruments, 91(2020).

[236] FU X, WANG E, ZHAO Y et al. Direct visualization of electromagnetic wave dynamics by laser-free ultrafast electron microscopy[J]. Science Advances, 6(2020).

[237] LASSISE A, MUTSAERS P H A, LUITEN O J. Compact， low power radio frequency cavity for femtosecond electron microscopy[J]. Review of Scientific Instruments, 83(2012).

[238] VERHOEVEN W, J F MVAN RENS, KIEFT E R et al. High quality ultrafast transmission electron microscopy using resonant microwave cavities[J]. Ultramicroscopy, 188, 85-89(2018).

[239] MOHAMMED O F, YANG D S et al. 4D scanning ultrafast electron microscopy： visualization of materials surface dynamics[J]. Journal of the American Chemical Society, 133, 7708-7711(2011).

[240] LIAO B, NAJAFI E. Scanning ultrafast electron microscopy： A novel technique to probe photocarrier dynamics with high spatial and temporal resolutions[J]. Materials Today Physics, 2, 46-53(2017).

[241] NAJAFI E, SCARBOROUGH T D, TANG J et al. Four-dimensional imaging of carrier interface dynamics in p-n junctions[J]. Science, 347, 164-167(2015).

[242] LIAO B, ZHAO H, NAJAFI E et al. Spatial-temporal imaging of anisotropic photocarrier dynamics in black phosphorus[J]. Nano Letters, 17, 3675-3680(2017).

[243] ZANI M, SALA V, IRDE G et al. Charge dynamics in aluminum oxide thin film studied by ultrafast scanning electron microscopy[J]. Ultramicroscopy, 187, 93-97(2018).

[244] SUN J, MELNIKOV V A, KHAN J I et al. Real-space imaging of carrier dynamics of materials surfaces by second-generation four-dimensional scanning ultrafast electron microscopy[J]. Journal of Physical Chemistry Letters, 6, 3884-3890(2015).

[245] EL-ZOHRY A M, SHAHEEN B S, BURLAKOV V M et al. Extraordinary carrier diffusion on CdTe surfaces uncovered by 4D electron microscopy[J]. Chem, 5, 706-718(2019).

[246] BOSE R, ADHIKARI A, BURLAKOV V M et al. Imaging localized energy states in silicon-doped InGaN nanowires using 4D electron microscopy[J]. ACS Energy Letters, 3, 476-481(2018).

[247] STECKENBORN A, MUNZEL H, BIMBERG D. Cathodoluminescence lifetime pattern of GaAs-surfaces around dislocations[J]. Journal of Luminescence, 24, 351-354(1981).

[248] HASTENRATH M, KUBALEK E. Time-resolved cathodoluminescence in scanning electron-microscopy[J]. Scanning Electron Microscopy, 1, 157-173(1982).

[249] MYHAJLENKO S, KE W K. Time-resolved cathodoluminescence by delayed coincidence[J]. Journal of Physics E-Scientific Instruments, 17, 200-203(1984).

[250] MERANO M, SONDEREGGER S, CROTTINI A et al. Probing carrier dynamics in nanostructures by picosecond cathodoluminescence[J]. Nature, 438, 479-482(2005).

[251] FURUSAWA K, ISHIKAWA Y, TASHIRO M et al. Local carrier dynamics around the sub-surface basal-plane stacking faults of GaN studied by spatio-time-resolved cathodoluminescence using a front-excitation-type photoelectron-gun[J]. Applied Physics Letters, 103(2013).

[252] SHAHMOHAMMADI M, JACOPIN G, FU X et al. Exciton hopping probed by picosecond time-resolved cathodoluminescence[J]. Applied Physics Letters, 107, 141101(2015).

[253] FU X, JACOPIN G, SHAHMOHAMMADI M et al. Exciton drift in semiconductors under uniform strain gradients： Application to bent ZnO microwires[J]. ACS Nano, 8, 3412-3420(2014).