3D Coincidence Imaging Disentangles Intense Field Double Detachment of SF₆^–

Abstract

The efficient intense field double detachment of molecular anions observed in SF6(–) is studied by 3D coincidence imaging of the dissociation products. The dissociation anisotropy and kinetic energy release distributions are determined for the energetically lowest double detachment channel by virtue of disentangling the SF5(+) + F fragmentation products. The observed nearly isotropic dissociation with respect to the linear laser polarization and surprisingly high kinetic energy release events suggest that the dissociation occurs on a highly excited state. Rydberg (SF6(+))* states composed of a highly repulsive dication core and a Rydberg electron are proposed to explain the observed kinetic energy release, accounting also for the efficient production of all possible cationic fragments at equivalent laser intensities.

Time-resolving the ultrafast H2 roaming chemistry and H3+ formation using extreme-ultraviolet pulses

“…The nIR beam is mildly focused behind the spectrometer with a 610 mm lens,~203 mm behind the spectrometer, such that at the nIR beam is inside the EUV, as validated by using the spectrometer to image the parent ion birth positions. The cationic products are accelerated from the interaction volume towards a time and position sensitive detector, allowing 3D coincidence imaging of the ion recoil velocities [43][44][45] . Low count rate and center of mass momentum conservation are used to suppress random coincidence cation signal due to dissociative ionization of two different parent molecules.…”

Simultaneous 3D coincidence imaging of cationic, anionic, and neutral photo-fragments

“…In our experimental setup, [28][29][30][31][32] anions are produced in a cold ion source, equipped with a pulsed electron gun and an Even-Lavie pulsed valve. 34 by dissociative electron attachment to the NF precursor sample, 35,36 supersonically expanded with Ar carrier gas.…”

“…We use the correlation of the amplitude of the electronic timing signal and the brightness of the optical position signal of a specific hit to correlate the times and positions of multiple hits. 32,[40][41][42] In Sec. III, we explain how the position and timing information are analyzed to extract the 3D KER.…”

“…[25][26][27] Using a fast anion beam target and a similar concept of an electrostatic spectrometer, we are able to investigate different competing dissociation and electron detachment channels in intense field interaction with atomic, molecular, and cluster anions. [28][29][30][31][32][33] The photofragment spectrometer design allows coincidence detection of all the possible dissociation products on the same detector, including the anionic, cationic, and neutral fragments. In the present study, we describe the design, calibration, and optimization of the photofragment spectrometer as well as an analytic model for extracting channel specific KER spectra from 3D coincidence imaging data.…”

Изменение Нормальных Координат И Геометрических Параметров Молекулы В Лазерном Поле

“…Среди достижений последних лет можно указать исследование лазерного химического синтеза [1,2], лазерный контроль движения молекуляр-ных электронов [3,4] и изменения оптических свойств газа когерентно вращающихся молекул [5][6][7][8], спектро-скопию комбинационного [9] и когерентного антисток-сова рассеяния света [10], перегруппировку атомов при лазерной фрагментации молекул [11], наблюдение двухэлектронного отрыва от анионов SF − 6 [12,13] и F − (NF 3 ) n [14]. В недавнем эксперименте [15] была продемонстри-рована важная роль " одетого полем" атома при рас-сеянии на нем электрона в поле лазерного излучения (laser-assisted electron scattering, LAES), теоретически рассмотренного в работе [16].…”