Coherent phase control of internal conversion in pyrazine

Robert J. Gordon, Zhan Hu, Tamar Seideman, Sima Singha, Maxim Sukharev, Youbo Zhao

Research output: Contribution to journalArticle

2 Citations (Scopus)

Abstract

Shaped ultrafast laser pulses were used to study and control the ionization dynamics of electronically excited pyrazine in a pump and probe experiment. For pump pulses created without feedback from the product signal, the ion growth curve (the parent ion signal as a function of pump/probe delay) was described quantitatively by the classical rate equations for internal conversion of the S<inf>2</inf> and S<inf>1</inf> states. Very different, non-classical behavior was observed when a genetic algorithm (GA) employing phase-only modulation was used to minimize the ion signal at some pre-determined target time, T. Two qualitatively different control mechanisms were identified for early (T < 1.5 ps) and late (T > 1.5 ps) target times. In the former case, the ion signal was largely suppressed for t < T, while for t 蠑 T, the ion signal produced by the GA-optimized pulse and a transform limited (TL) pulse coalesced. In contrast, for T > 1.5 ps, the ion growth curve followed the classical rate equations for t < T, while for t 蠑 T, the quantum yield for the GA-optimized pulse was much smaller than for a TL pulse. We interpret the first type of behavior as an indication that the wave packet produced by the pump laser is localized in a region of the S<inf>2</inf> potential energy surface where the vertical ionization energy exceeds the probe photon energy, whereas the second type of behavior may be described by a reduced absorption cross section for S<inf>0</inf> → S<inf>2</inf> followed by incoherent decay of the excited molecules. Amplitude modulation observed in the spectrum of the shaped pulse may have contributed to the control mechanism, although this possibility is mitigated by the very small focal volume of the probe laser.

Original languageEnglish (US)
Article number144311
JournalJournal of Chemical Physics
Volume142
Issue number14
DOIs
StatePublished - Apr 14 2015

Fingerprint

Pyrazines
Phase control
phase control
pyrazines
internal conversion
Ions
probes
Pumps
pumps
ions
pulses
Ultrafast lasers
ionization
Potential energy surfaces
Amplitude modulation
Ionization potential
curves
genetic algorithms
absorption cross sections
Ionization

ASJC Scopus subject areas

  • Physics and Astronomy(all)
  • Physical and Theoretical Chemistry

Cite this

Gordon, R. J., Hu, Z., Seideman, T., Singha, S., Sukharev, M., & Zhao, Y. (2015). Coherent phase control of internal conversion in pyrazine. Journal of Chemical Physics, 142(14), [144311]. https://doi.org/10.1063/1.4916642

Coherent phase control of internal conversion in pyrazine. / Gordon, Robert J.; Hu, Zhan; Seideman, Tamar; Singha, Sima; Sukharev, Maxim; Zhao, Youbo.

In: Journal of Chemical Physics, Vol. 142, No. 14, 144311, 14.04.2015.

Research output: Contribution to journalArticle

Gordon, RJ, Hu, Z, Seideman, T, Singha, S, Sukharev, M & Zhao, Y 2015, 'Coherent phase control of internal conversion in pyrazine', Journal of Chemical Physics, vol. 142, no. 14, 144311. https://doi.org/10.1063/1.4916642
Gordon, Robert J. ; Hu, Zhan ; Seideman, Tamar ; Singha, Sima ; Sukharev, Maxim ; Zhao, Youbo. / Coherent phase control of internal conversion in pyrazine. In: Journal of Chemical Physics. 2015 ; Vol. 142, No. 14.
@article{18e8b4e04a7a43809d2e18e587e73f88,
title = "Coherent phase control of internal conversion in pyrazine",
abstract = "Shaped ultrafast laser pulses were used to study and control the ionization dynamics of electronically excited pyrazine in a pump and probe experiment. For pump pulses created without feedback from the product signal, the ion growth curve (the parent ion signal as a function of pump/probe delay) was described quantitatively by the classical rate equations for internal conversion of the S2 and S1 states. Very different, non-classical behavior was observed when a genetic algorithm (GA) employing phase-only modulation was used to minimize the ion signal at some pre-determined target time, T. Two qualitatively different control mechanisms were identified for early (T < 1.5 ps) and late (T > 1.5 ps) target times. In the former case, the ion signal was largely suppressed for t < T, while for t 蠑 T, the ion signal produced by the GA-optimized pulse and a transform limited (TL) pulse coalesced. In contrast, for T > 1.5 ps, the ion growth curve followed the classical rate equations for t < T, while for t 蠑 T, the quantum yield for the GA-optimized pulse was much smaller than for a TL pulse. We interpret the first type of behavior as an indication that the wave packet produced by the pump laser is localized in a region of the S2 potential energy surface where the vertical ionization energy exceeds the probe photon energy, whereas the second type of behavior may be described by a reduced absorption cross section for S0 → S2 followed by incoherent decay of the excited molecules. Amplitude modulation observed in the spectrum of the shaped pulse may have contributed to the control mechanism, although this possibility is mitigated by the very small focal volume of the probe laser.",
author = "Gordon, {Robert J.} and Zhan Hu and Tamar Seideman and Sima Singha and Maxim Sukharev and Youbo Zhao",
year = "2015",
month = "4",
day = "14",
doi = "10.1063/1.4916642",
language = "English (US)",
volume = "142",
journal = "Journal of Chemical Physics",
issn = "0021-9606",
publisher = "American Institute of Physics Publising LLC",
number = "14",

}

TY - JOUR

T1 - Coherent phase control of internal conversion in pyrazine

AU - Gordon, Robert J.

AU - Hu, Zhan

AU - Seideman, Tamar

AU - Singha, Sima

AU - Sukharev, Maxim

AU - Zhao, Youbo

PY - 2015/4/14

Y1 - 2015/4/14

N2 - Shaped ultrafast laser pulses were used to study and control the ionization dynamics of electronically excited pyrazine in a pump and probe experiment. For pump pulses created without feedback from the product signal, the ion growth curve (the parent ion signal as a function of pump/probe delay) was described quantitatively by the classical rate equations for internal conversion of the S2 and S1 states. Very different, non-classical behavior was observed when a genetic algorithm (GA) employing phase-only modulation was used to minimize the ion signal at some pre-determined target time, T. Two qualitatively different control mechanisms were identified for early (T < 1.5 ps) and late (T > 1.5 ps) target times. In the former case, the ion signal was largely suppressed for t < T, while for t 蠑 T, the ion signal produced by the GA-optimized pulse and a transform limited (TL) pulse coalesced. In contrast, for T > 1.5 ps, the ion growth curve followed the classical rate equations for t < T, while for t 蠑 T, the quantum yield for the GA-optimized pulse was much smaller than for a TL pulse. We interpret the first type of behavior as an indication that the wave packet produced by the pump laser is localized in a region of the S2 potential energy surface where the vertical ionization energy exceeds the probe photon energy, whereas the second type of behavior may be described by a reduced absorption cross section for S0 → S2 followed by incoherent decay of the excited molecules. Amplitude modulation observed in the spectrum of the shaped pulse may have contributed to the control mechanism, although this possibility is mitigated by the very small focal volume of the probe laser.

AB - Shaped ultrafast laser pulses were used to study and control the ionization dynamics of electronically excited pyrazine in a pump and probe experiment. For pump pulses created without feedback from the product signal, the ion growth curve (the parent ion signal as a function of pump/probe delay) was described quantitatively by the classical rate equations for internal conversion of the S2 and S1 states. Very different, non-classical behavior was observed when a genetic algorithm (GA) employing phase-only modulation was used to minimize the ion signal at some pre-determined target time, T. Two qualitatively different control mechanisms were identified for early (T < 1.5 ps) and late (T > 1.5 ps) target times. In the former case, the ion signal was largely suppressed for t < T, while for t 蠑 T, the ion signal produced by the GA-optimized pulse and a transform limited (TL) pulse coalesced. In contrast, for T > 1.5 ps, the ion growth curve followed the classical rate equations for t < T, while for t 蠑 T, the quantum yield for the GA-optimized pulse was much smaller than for a TL pulse. We interpret the first type of behavior as an indication that the wave packet produced by the pump laser is localized in a region of the S2 potential energy surface where the vertical ionization energy exceeds the probe photon energy, whereas the second type of behavior may be described by a reduced absorption cross section for S0 → S2 followed by incoherent decay of the excited molecules. Amplitude modulation observed in the spectrum of the shaped pulse may have contributed to the control mechanism, although this possibility is mitigated by the very small focal volume of the probe laser.

UR - http://www.scopus.com/inward/record.url?scp=84928474129&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84928474129&partnerID=8YFLogxK

U2 - 10.1063/1.4916642

DO - 10.1063/1.4916642

M3 - Article

AN - SCOPUS:84928474129

VL - 142

JO - Journal of Chemical Physics

JF - Journal of Chemical Physics

SN - 0021-9606

IS - 14

M1 - 144311

ER -