Photodissociation Dynamics of OCS at 217 nm

Abstract

The S(1 D 2)+CO(X 1 Σ +) product channel from photodissociation of OCS at 217 nm has been measured using the DC slice velocity map imaging (VMI) technique in combination with resonance enhanced multiphoton ionization (REMPI). Two different REMPI intermediate states (1 F 3 and 1 P 1) and several pump-probe laser polarization geometries are used to detect the angular momentum polarization of the photofragmented S(1 D 2). The molecularframe polarization parameters, as well as the laboratory-frame anisotropy parameters, for individual rotational states of co-fragment CO, are determined using two different full quantum theories. The measured total kinetic energy release spectrum from photodissociation of OCS indicates two dissociation channels, corresponding to the fast and slow recoiling velocities of S(1 D 2), respectively. The slow channel is concluded to originate from an initial photoexcitation to the A(1 A ′) state, followed by a non-adiabatic transition to the ground state. The fast channel is found to follow a coherent excitation to A(1 A ′) and B(1 A ′′) states, where contributions of the two states are almost equal at 217 nm. The determined alignment and anisotropy parameters further indicate that the slow channel follows an incoherent excitation, while the fast channel follows a coherent excitation to A(1 A ′) and B(1 A ′′) states with a phase difference of π/2.

Ultraviolet photodissociation dynamics of m-bromofluorobenzene at around 240 nm

“…Experiments are performed using our home-made DC-slice velocity map imaging setup, details of which can be found in our recent publications [15][16][17]. Briefly, a gas mixture of 1% 3-BrFPh vapor seeded in argon at a stagnation pressure of ∼3 bar is supersonically expanded into the first vacuum chamber through a pulsed nozzle (General Valve, Series 9, 0.25 mm orifice) and then skimmed by a 1 mm skimmer before entering the second differentially pumped chamber.…”

Observation of rovibrationally coupled bi-modality and speed-dependent orientation in DEA dynamics of OCS: reveals partial correlations among point group symmetries

“…Nevertheless, the neutral di-atomic counterpart (CO) can be fragmented with such highly populated rotational states, which arises due to rovibronically coupled strong bending forces in triatomic OCS [54]. A few reports on photodissociation and DEA to OCS [32,33,[55][56][57][58][59][60][61] reported that CO fragments are dominantly associated with highly excited rotational levels in the vibrational ground state, which confirms that CO stretching acts as a spectator in the dynamics. Our observations agree with such reports for rovibronically coupled high momentum bands.…”