Acetone Non-adiabatic Rydberg State Dynamics Studied by Femtosecond Photoelectron-photoion Coincidence Spectroscopy

Research output: Contribution to conferenceAbstractResearchpeer-review

Abstract

For the investigation of photochemical processes with time-resolved photo-ionization spectroscopy, it is essential to
obtain unequivocal experimental information about the fragmentation dynamics. Photoexcitation of acetone molecules to
high-lying Rydberg states triggers complex relaxation dynamics which are governed by Rydberg-valence couplings. We
apply time-resolved photoelectron-photoion coincidence (PEPICO) detection to disentangle parallel ionization channels
and to follow the fragmentation and relaxation behavior of each channel separately [1]. Photoexcited population
undergoes internal conversion to lower Rydberg states for which a sequential decay model reveals state-dependent decay
time constants ranging from 100 to 300 fs, following clear trends [3]. The corresponding non-adiabatic dynamics cause
the conversion of electronic to vibrational energy, leading to fragmentation after ionization to the cationic ground state,
for which the activation threshold can be accurately determined to be (0.79±0.04) EV [2]. Additionally, we observe a
channel facilitating fragmentation of the neutral molecule (before ionization) via a Norrish-Type-I reaction [1]. These
results demonstrate that in the complex situation of multiple, parallel relaxation pathways, less-differential probe
techniques might not allow the unambiguous interpretation of transient signals.
Original languageEnglish
Pages56
Publication statusPublished - 26 Mar 2018
EventBIT´s 6th Annual Conference of AnalytiX-2018: Faster, More Accurate, More Sensitive - Miami Marriott Dadeland, Miami, United States
Duration: 26 Mar 201828 Mar 2018
Conference number: 6
http://www.bitcongress.com/analytix2018/

Conference

ConferenceBIT´s 6th Annual Conference of AnalytiX-2018
CountryUnited States
CityMiami
Period26/03/1828/03/18
Internet address

Fields of Expertise

  • Advanced Materials Science

Cite this

Acetone Non-adiabatic Rydberg State Dynamics Studied by Femtosecond Photoelectron-photoion Coincidence Spectroscopy. / Koch, Markus; Cesnik, Stefan; Heim, Pascal; Ranftl, Sascha; Thaler, Bernhard; Ernst, Wolfgang E.

2018. 56 Abstract from BIT´s 6th Annual Conference of AnalytiX-2018, Miami, United States.

Research output: Contribution to conferenceAbstractResearchpeer-review

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abstract = "For the investigation of photochemical processes with time-resolved photo-ionization spectroscopy, it is essential toobtain unequivocal experimental information about the fragmentation dynamics. Photoexcitation of acetone molecules tohigh-lying Rydberg states triggers complex relaxation dynamics which are governed by Rydberg-valence couplings. Weapply time-resolved photoelectron-photoion coincidence (PEPICO) detection to disentangle parallel ionization channelsand to follow the fragmentation and relaxation behavior of each channel separately [1]. Photoexcited populationundergoes internal conversion to lower Rydberg states for which a sequential decay model reveals state-dependent decaytime constants ranging from 100 to 300 fs, following clear trends [3]. The corresponding non-adiabatic dynamics causethe conversion of electronic to vibrational energy, leading to fragmentation after ionization to the cationic ground state,for which the activation threshold can be accurately determined to be (0.79±0.04) EV [2]. Additionally, we observe achannel facilitating fragmentation of the neutral molecule (before ionization) via a Norrish-Type-I reaction [1]. Theseresults demonstrate that in the complex situation of multiple, parallel relaxation pathways, less-differential probetechniques might not allow the unambiguous interpretation of transient signals.",
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T1 - Acetone Non-adiabatic Rydberg State Dynamics Studied by Femtosecond Photoelectron-photoion Coincidence Spectroscopy

AU - Koch, Markus

AU - Cesnik, Stefan

AU - Heim, Pascal

AU - Ranftl, Sascha

AU - Thaler, Bernhard

AU - Ernst, Wolfgang E.

PY - 2018/3/26

Y1 - 2018/3/26

N2 - For the investigation of photochemical processes with time-resolved photo-ionization spectroscopy, it is essential toobtain unequivocal experimental information about the fragmentation dynamics. Photoexcitation of acetone molecules tohigh-lying Rydberg states triggers complex relaxation dynamics which are governed by Rydberg-valence couplings. Weapply time-resolved photoelectron-photoion coincidence (PEPICO) detection to disentangle parallel ionization channelsand to follow the fragmentation and relaxation behavior of each channel separately [1]. Photoexcited populationundergoes internal conversion to lower Rydberg states for which a sequential decay model reveals state-dependent decaytime constants ranging from 100 to 300 fs, following clear trends [3]. The corresponding non-adiabatic dynamics causethe conversion of electronic to vibrational energy, leading to fragmentation after ionization to the cationic ground state,for which the activation threshold can be accurately determined to be (0.79±0.04) EV [2]. Additionally, we observe achannel facilitating fragmentation of the neutral molecule (before ionization) via a Norrish-Type-I reaction [1]. Theseresults demonstrate that in the complex situation of multiple, parallel relaxation pathways, less-differential probetechniques might not allow the unambiguous interpretation of transient signals.

AB - For the investigation of photochemical processes with time-resolved photo-ionization spectroscopy, it is essential toobtain unequivocal experimental information about the fragmentation dynamics. Photoexcitation of acetone molecules tohigh-lying Rydberg states triggers complex relaxation dynamics which are governed by Rydberg-valence couplings. Weapply time-resolved photoelectron-photoion coincidence (PEPICO) detection to disentangle parallel ionization channelsand to follow the fragmentation and relaxation behavior of each channel separately [1]. Photoexcited populationundergoes internal conversion to lower Rydberg states for which a sequential decay model reveals state-dependent decaytime constants ranging from 100 to 300 fs, following clear trends [3]. The corresponding non-adiabatic dynamics causethe conversion of electronic to vibrational energy, leading to fragmentation after ionization to the cationic ground state,for which the activation threshold can be accurately determined to be (0.79±0.04) EV [2]. Additionally, we observe achannel facilitating fragmentation of the neutral molecule (before ionization) via a Norrish-Type-I reaction [1]. Theseresults demonstrate that in the complex situation of multiple, parallel relaxation pathways, less-differential probetechniques might not allow the unambiguous interpretation of transient signals.

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SP - 56

ER -