Time-Resolved Photodetachment Anisotropy: Gas-Phase Rotational and Vibrational Dynamics of the Fluorescein Anion

Abstract

. (2015) 'Time-resolved photodetachment anisotropy : gas-phase rotational and vibrational dynamics of the uorescein anion.', Journal of physical chemistry letters., 6 (1). pp. 189-194. Further information on publisher's website: Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-pro t purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details.

Rotational and vibrational dynamics in the excited electronic state of deprotonated and protonated fluorescein studied by time-resolved photofragmentation in an ion trap

“…This modulation disappears within ∼6 ps. A similar dependence of a transient signal on the relative polarization orientation between pump (495 nm) and probe (400 nm) pulses, as well as a strong modulation was observed for [FL − H] − in the gas-phase applying TR-PA 22 . In TR-PA experiments, however, the total photoelectron signal intensity exhibited (1) a stronger dependence on the relative laser polarization, (2) the trace for parallel pump-probe polarization featured a higher intensity (compared to the signal at perpendicular polarization), and (3) the oscillatory component (of similar frequency) disappeared on a shorter timescale (within ∼3 ps).…”

“…However, the absolute ion signal intensities are subject to significant fluctuations of ∼10% for the parent ion and ∼15% for the main fragment ion, so that a quantitative analysis of the photodetachment yield from our data is not meaningful. Nevertheless, recently the time-resolved photodetachment of [FL − H] − was studied employing 495 nm (∼242 kJ/mol) pump/400 nm (∼300 kJ/mol) probe laser pulses 22 . The photoelectron yield under those excitation conditions was not given, but it is known (from studies on e.g., the chromophore of the green fluorescent protein) 35 that at higher photon energies photodetachment may prevail over possible nuclear fragmentation processes.…”

“…We therefore used the same method of analysis to disentangle rotational from population dynamics, as described and applied successfully in Ref. 22. Briefly, this analysis originates from TR-FA and is implemented by measuring transient signals at parallel and perpendicular relative linear laser polarization.…”

“…The importance of the latter applications, their perspective for Förster resonance energy transfer (FRET) studies, 15–17 and furthermore, the search for insight into the influence of solvation on the different prototopic FL forms has sparked interest in gas phase studies coupled with mass spectrometric or fluorescence detection 18–21 . In addition, recently, it was convincingly demonstrated that a gas-phase analogue to TR-FA is possible by implementation of a femtosecond time-resolved photodetachment anisotropy (TR-PA) scheme 22 . In that report, rotational and vibrational wavepacket dynamics were observed for [FL-H] − by velocity-map imaging detection of photoelectrons 22 …”

Photoelectron imaging as a probe of the repulsive Coulomb barrier in the photodetachment of antimony tartrate dianions

“…A route to enable more direct comparisons would be by pre-alignment the dianion before photodetachment, for example, using resonant excitation if the dianion supports a bound electronic excited state. 10,45 However, even in such a case, knowledge of the differential cross section for photodetachment alignment from the excited state is still required.…”