Resonance enhanced multiphoton ionization spectroscopy of jet cooled C3212S2 and C3212S32S from 45 500 to 48 000 cm−1

Abstract

The (1+1) resonance enhanced multiphoton ionization spectra of jet-cooled CS2 were obtained between 45 500 and 48 000 cm−1 (220–208 nm) for the two isotopomers C3212S2 and C3212S32S. With the use of different expansion gases which resulted in varying degrees of vibrational cooling and the comparison of the two isotopomer spectra, a partial assignment of the C̃ 1B2–X̃ 1Σg+ transition was obtained. The electronic origin of this transition is confirmed to lie at 46 248.7 cm−1 and values for the predissociation lifetimes for the upper state for 34 vibrational bands and isotopomer shifts of seven vibrational levels of the B21 state are presented. The lifetimes of the Σ0 bands were found to be larger than those of corresponding Π1 and Δ2 bands. A simulation of the spectrum, which used the harmonic approximation, is in qualitative agreement with the band positions and shifts, but quantitative disagreement between the values leads us to conclude that a normal mode analysis is not appropriate to describe the low vibrational levels of the B21 state. The results presented increase our understanding of the low-lying predissociating levels of CS2, which will be of use in future photofragment studies.

K-Dependent Predissociation Dynamics of CS2 in the 210−216 nm Region

“…The PHOFEX spectrum of CS 2 was obtained by fixing the wavelength of probe laser at 257.6 nm and scanning the wavelength of dissociation laser in the range of 209.5−216 nm, as shown in Figure . The spectral assignment was adopted from previous works by Douglas and Zanon 1 and Beatty et al Due to the near degeneracy of ν 1 and ν 2 vibrational modes at the 1 B 2 ( 1 Σ u + ) state, the vibrational levels could not be presented by normal mode ( v 1 , v 2 , v 3 ), and were just marked as a, b, c..., in the order of increasing energy. Since spectral analysis showed that CS 2 molecule at the 1 B 2 ( 1 Σ u + ) state was a near-prolate symmetric top, the electronic transition 1 B 2 ( 1 Σ u + ) ← X( 1 Σ g + ) of this spectrum is parallel.…”

“…The determined lifetimes of our interested vibrational levels via excitations of different quantum number K are listed in Table . The lifetimes reported in refs , , and 17 are also listed in this table for comparison. Generally, the majority of the predissociation lifetimes from this work agree within experimental error with those previously reported.…”

“…The strongest absorption band of CS 2 molecule in the wavelength range of 185−230 nm, which was assigned as 1 B 2 ( 1 Σ u + ) ← XΣ g + parallel electronic transition, has been investigated by numerous authors. − The band origin, equilibrium bond length and angle, and the vibrational frequencies of the 1 B 2 ( 1 Σ u + ) state were determined from the spectrum in this range. The spectroscopic analyses indicate that there is an energetic barrier in the 1 B 2 ( 1 Σ u + ) state located at around 204 nm for molecular structure changing from bent to linear geometry. ,, Extensive studies have been performed on the dissociation dynamics of CS 2 in the 1 B 2 ( 1 Σ u + ) state. − It has been known that CS 2 molecule in this excited state is predissociative via two parallel pathways, CS 2 ( 1 B 2 ( 1 Σ u + )) → CS(X 1 Σ + ) + S( 3 P) and CS 2 ( 1 B 2 ( 1 Σ u + )) → CS(X 1 Σ + ) + S( 1 D).…”

Ultrafast dynamics and dissociative ionization of CS2 molecules studied via the femtosecond pump-probe method

“…A halfwave plate and a Glan prism were inserted into each laser beam as a means of varying laser intensity. The laser intensities used in this work at 267 nm and 400 nm were estimated to be 4×10 12 and 2×10 13 W/cm 2 , respectively. The ions produced were extracted and accelerated by optical ion lens and were detected using dual micro-channel-plates at the end of the 1-m flight.…”

“…Efforts have also been made to understand the structure and non-adiabatic dynamics of the predissociation 1 B 2 ( 1 Σ u + ) state over the wavelength range 180-230 nm. These include high-resolution absorption [11], resonance enhanced multiphoton ionization (REMPI) [12] and laser induced fluorescence [13] spectroscopic studies, and dynamic studies [14], to determine the channel branch ratio, the fragment energy partition, and the lifetime. Rydberg series were investigated in a wide range of excitation energies using the (2+1) and (3+1) REMPI methods [15].…”