Coherent imaging of an attosecond electron wave packet. Villeneuve, D M, Hockett, P., Vrakking, M J J, & Niikura, H. Science, 356(6343):1150–1153, June, 2017. doi abstract bibtex Electrons detached from atoms or molecules by photoionization carry information about the quantum state from which they originate, as well as the continuum states into which they are released. Generally, the photoelectron momentum distribution is composed of a coherent sum of angular momentum components, each with an amplitude and phase. Here we show, by using photoionization of neon, that a train of attosecond pulses synchronized with an infrared laser field can be used to disentangle these angular momentum components. Two-color, two-photon ionization via a Stark-shifted intermediate state creates an almost pure f-wave with a magnetic quantum number of zero. Interference of the f-wave with a spherically symmetric s-wave provides a holographic reference that enables phase-resolved imaging of the f-wave. I n the Copenhagen interpretation of quantum mechanics, a particle is fully described by its complex wave function Y, which is charac-terized by both an amplitude and phase. How-ever, only the square modulus of the wave function, |Y| 2 , can be directly observed (1, 2). Re-cent developments in attosecond technology based on electron-ion recollision (3) have pro-vided experimental tools for the imaging of the electronic wave function (not its square) in bound states or ionization continua. High-harmonic spec-troscopy on aligned molecules was used to re-construct the highest-occupied molecular orbital of nitrogen (4, 5) and to observe charge migra-tion (6). Strong-field tunneling was used to mea-sure the square modulus of the highest-occupied molecular orbital for selected molecules (7). Fur-thermore, recollision holography (8, 9) permitted a measurement of the phase and amplitude of a continuum electron generated in an intense laser field. Complementary to recollision-based measure-ments, photoelectron spectroscopy with atto-second extreme ultraviolet (XUV) pulses has also measured photoelectron wave packets in continuum states (10–16) by exploiting quantum interferences (17–19). However, decomposition of the wave function of an ejected photoelec-tron into angular momentum eigenstates with a fully characterized amplitude and phase is more difficult. First, in general, a one-photon transition with linearly polarized light gener-ates two orbital angular momentum (') states, according to the selection rule D ' $\sfrac{1}{4}$ T1. Second, because the initial state has a ð2' þ 1Þ-fold de-generacy (labeled by m, the magnetic quan-tum number) and because m is conserved for interactions with linearly polarized light, photo-electron waves with a range of m are produced. Hence, the photoelectron momentum distribution contains a sum of contributions from different initial states, each of which is a coherent sum of different angular momentum components, making it difficult to decompose the continuum state into individual angular momentum com-ponents (20–22). Here we preferentially create an almost pure f-wave continuum wave function with m = 0 in neon by using an attosecond XUV pulse train synchronized with an infrared (IR) laser pulse through the process of high-harmonic genera-tion. The isolation of the f-wave with m = 0 is attributed to the XUV excitation to a resonant bound state that is Stark-shifted by the IR field.
@Article{Villeneuve2017,
author = {Villeneuve, D M and Hockett, Paul and Vrakking, M J J and Niikura, Hiromichi},
journal = {Science},
title = {{Coherent imaging of an attosecond electron wave packet}},
year = {2017},
issn = {0036-8075},
month = jun,
number = {6343},
pages = {1150--1153},
volume = {356},
abstract = {Electrons detached from atoms or molecules by photoionization carry information about the quantum state from which they originate, as well as the continuum states into which they are released. Generally, the photoelectron momentum distribution is composed of a coherent sum of angular momentum components, each with an amplitude and phase. Here we show, by using photoionization of neon, that a train of attosecond pulses synchronized with an infrared laser field can be used to disentangle these angular momentum components. Two-color, two-photon ionization via a Stark-shifted intermediate state creates an almost pure f-wave with a magnetic quantum number of zero. Interference of the f-wave with a spherically symmetric s-wave provides a holographic reference that enables phase-resolved imaging of the f-wave. I n the Copenhagen interpretation of quantum mechanics, a particle is fully described by its complex wave function Y, which is charac-terized by both an amplitude and phase. How-ever, only the square modulus of the wave function, |Y| 2 , can be directly observed (1, 2). Re-cent developments in attosecond technology based on electron-ion recollision (3) have pro-vided experimental tools for the imaging of the electronic wave function (not its square) in bound states or ionization continua. High-harmonic spec-troscopy on aligned molecules was used to re-construct the highest-occupied molecular orbital of nitrogen (4, 5) and to observe charge migra-tion (6). Strong-field tunneling was used to mea-sure the square modulus of the highest-occupied molecular orbital for selected molecules (7). Fur-thermore, recollision holography (8, 9) permitted a measurement of the phase and amplitude of a continuum electron generated in an intense laser field. Complementary to recollision-based measure-ments, photoelectron spectroscopy with atto-second extreme ultraviolet (XUV) pulses has also measured photoelectron wave packets in continuum states (10--16) by exploiting quantum interferences (17--19). However, decomposition of the wave function of an ejected photoelec-tron into angular momentum eigenstates with a fully characterized amplitude and phase is more difficult. First, in general, a one-photon transition with linearly polarized light gener-ates two orbital angular momentum (') states, according to the selection rule D ' $\sfrac{1}{4}$ T1. Second, because the initial state has a {\dh}2' {\th} 1{\TH}-fold de-generacy (labeled by m, the magnetic quan-tum number) and because m is conserved for interactions with linearly polarized light, photo-electron waves with a range of m are produced. Hence, the photoelectron momentum distribution contains a sum of contributions from different initial states, each of which is a coherent sum of different angular momentum components, making it difficult to decompose the continuum state into individual angular momentum com-ponents (20--22). Here we preferentially create an almost pure f-wave continuum wave function with m = 0 in neon by using an attosecond XUV pulse train synchronized with an infrared (IR) laser pulse through the process of high-harmonic genera-tion. The isolation of the f-wave with m = 0 is attributed to the XUV excitation to a resonant bound state that is Stark-shifted by the IR field.},
doi = {10.1126/science.aam8393},
groups = {[paul:]},
timestamp = {2018.07.12},
}
Downloads: 0
{"_id":"MzAgcx4a7gjS4KP8S","bibbaseid":"villeneuve-hockett-vrakking-niikura-coherentimagingofanattosecondelectronwavepacket-2017","downloads":0,"creationDate":"2017-06-28T19:43:47.651Z","title":"Coherent imaging of an attosecond electron wave packet","author_short":["Villeneuve, D M","Hockett, P.","Vrakking, M J J","Niikura, H."],"year":2017,"bibtype":"article","biburl":"http://github.com/phockett/UQO-group/raw/main/group_ongoing.bib","bibdata":{"bibtype":"article","type":"article","author":[{"propositions":[],"lastnames":["Villeneuve"],"firstnames":["D","M"],"suffixes":[]},{"propositions":[],"lastnames":["Hockett"],"firstnames":["Paul"],"suffixes":[]},{"propositions":[],"lastnames":["Vrakking"],"firstnames":["M","J","J"],"suffixes":[]},{"propositions":[],"lastnames":["Niikura"],"firstnames":["Hiromichi"],"suffixes":[]}],"journal":"Science","title":"Coherent imaging of an attosecond electron wave packet","year":"2017","issn":"0036-8075","month":"June","number":"6343","pages":"1150–1153","volume":"356","abstract":"Electrons detached from atoms or molecules by photoionization carry information about the quantum state from which they originate, as well as the continuum states into which they are released. Generally, the photoelectron momentum distribution is composed of a coherent sum of angular momentum components, each with an amplitude and phase. Here we show, by using photoionization of neon, that a train of attosecond pulses synchronized with an infrared laser field can be used to disentangle these angular momentum components. Two-color, two-photon ionization via a Stark-shifted intermediate state creates an almost pure f-wave with a magnetic quantum number of zero. Interference of the f-wave with a spherically symmetric s-wave provides a holographic reference that enables phase-resolved imaging of the f-wave. I n the Copenhagen interpretation of quantum mechanics, a particle is fully described by its complex wave function Y, which is charac-terized by both an amplitude and phase. How-ever, only the square modulus of the wave function, |Y| 2 , can be directly observed (1, 2). Re-cent developments in attosecond technology based on electron-ion recollision (3) have pro-vided experimental tools for the imaging of the electronic wave function (not its square) in bound states or ionization continua. High-harmonic spec-troscopy on aligned molecules was used to re-construct the highest-occupied molecular orbital of nitrogen (4, 5) and to observe charge migra-tion (6). Strong-field tunneling was used to mea-sure the square modulus of the highest-occupied molecular orbital for selected molecules (7). Fur-thermore, recollision holography (8, 9) permitted a measurement of the phase and amplitude of a continuum electron generated in an intense laser field. Complementary to recollision-based measure-ments, photoelectron spectroscopy with atto-second extreme ultraviolet (XUV) pulses has also measured photoelectron wave packets in continuum states (10–16) by exploiting quantum interferences (17–19). However, decomposition of the wave function of an ejected photoelec-tron into angular momentum eigenstates with a fully characterized amplitude and phase is more difficult. First, in general, a one-photon transition with linearly polarized light gener-ates two orbital angular momentum (') states, according to the selection rule D ' $\\sfrac{1}{4}$ T1. Second, because the initial state has a ð2' þ 1Þ-fold de-generacy (labeled by m, the magnetic quan-tum number) and because m is conserved for interactions with linearly polarized light, photo-electron waves with a range of m are produced. Hence, the photoelectron momentum distribution contains a sum of contributions from different initial states, each of which is a coherent sum of different angular momentum components, making it difficult to decompose the continuum state into individual angular momentum com-ponents (20–22). Here we preferentially create an almost pure f-wave continuum wave function with m = 0 in neon by using an attosecond XUV pulse train synchronized with an infrared (IR) laser pulse through the process of high-harmonic genera-tion. The isolation of the f-wave with m = 0 is attributed to the XUV excitation to a resonant bound state that is Stark-shifted by the IR field.","doi":"10.1126/science.aam8393","groups":"[paul:]","timestamp":"2018.07.12","bibtex":"@Article{Villeneuve2017,\n author = {Villeneuve, D M and Hockett, Paul and Vrakking, M J J and Niikura, Hiromichi},\n journal = {Science},\n title = {{Coherent imaging of an attosecond electron wave packet}},\n year = {2017},\n issn = {0036-8075},\n month = jun,\n number = {6343},\n pages = {1150--1153},\n volume = {356},\n abstract = {Electrons detached from atoms or molecules by photoionization carry information about the quantum state from which they originate, as well as the continuum states into which they are released. Generally, the photoelectron momentum distribution is composed of a coherent sum of angular momentum components, each with an amplitude and phase. Here we show, by using photoionization of neon, that a train of attosecond pulses synchronized with an infrared laser field can be used to disentangle these angular momentum components. Two-color, two-photon ionization via a Stark-shifted intermediate state creates an almost pure f-wave with a magnetic quantum number of zero. Interference of the f-wave with a spherically symmetric s-wave provides a holographic reference that enables phase-resolved imaging of the f-wave. I n the Copenhagen interpretation of quantum mechanics, a particle is fully described by its complex wave function Y, which is charac-terized by both an amplitude and phase. How-ever, only the square modulus of the wave function, |Y| 2 , can be directly observed (1, 2). Re-cent developments in attosecond technology based on electron-ion recollision (3) have pro-vided experimental tools for the imaging of the electronic wave function (not its square) in bound states or ionization continua. High-harmonic spec-troscopy on aligned molecules was used to re-construct the highest-occupied molecular orbital of nitrogen (4, 5) and to observe charge migra-tion (6). Strong-field tunneling was used to mea-sure the square modulus of the highest-occupied molecular orbital for selected molecules (7). Fur-thermore, recollision holography (8, 9) permitted a measurement of the phase and amplitude of a continuum electron generated in an intense laser field. Complementary to recollision-based measure-ments, photoelectron spectroscopy with atto-second extreme ultraviolet (XUV) pulses has also measured photoelectron wave packets in continuum states (10--16) by exploiting quantum interferences (17--19). However, decomposition of the wave function of an ejected photoelec-tron into angular momentum eigenstates with a fully characterized amplitude and phase is more difficult. First, in general, a one-photon transition with linearly polarized light gener-ates two orbital angular momentum (') states, according to the selection rule D ' $\\sfrac{1}{4}$ T1. Second, because the initial state has a {\\dh}2' {\\th} 1{\\TH}-fold de-generacy (labeled by m, the magnetic quan-tum number) and because m is conserved for interactions with linearly polarized light, photo-electron waves with a range of m are produced. Hence, the photoelectron momentum distribution contains a sum of contributions from different initial states, each of which is a coherent sum of different angular momentum components, making it difficult to decompose the continuum state into individual angular momentum com-ponents (20--22). Here we preferentially create an almost pure f-wave continuum wave function with m = 0 in neon by using an attosecond XUV pulse train synchronized with an infrared (IR) laser pulse through the process of high-harmonic genera-tion. The isolation of the f-wave with m = 0 is attributed to the XUV excitation to a resonant bound state that is Stark-shifted by the IR field.},\n doi = {10.1126/science.aam8393},\n groups = {[paul:]},\n timestamp = {2018.07.12},\n}\n\n","author_short":["Villeneuve, D M","Hockett, P.","Vrakking, M J J","Niikura, H."],"key":"Villeneuve2017","id":"Villeneuve2017","bibbaseid":"villeneuve-hockett-vrakking-niikura-coherentimagingofanattosecondelectronwavepacket-2017","role":"author","urls":{},"metadata":{"authorlinks":{"hockett, p":"https://bibbase.org/service/mendeley/929c804b-e5d8-3f59-bf8f-9e904e082c0f"}},"downloads":0},"search_terms":["coherent","imaging","attosecond","electron","wave","packet","villeneuve","hockett","vrakking","niikura"],"keywords":[],"authorIDs":["aPR7dPJNHWgr2zJ6a"],"dataSources":["6KGmJxs9RrDfHzcu8","ya2CyA73rpZseyrZ8","H7fwLrC4uE8sA55y4","74PaJ3jeYTJQFhBLi","Cyvp3egaEX9XcqyzN","9YtT85enAASHbgEpa","BqutdYRmHLywqGRJb"]}