Vacuum ultraviolet pulsed field ionization-photoelectron study of OCS in the energy range of 15–19 eV

Abstract

Pulsed field ionization-photoelectron bands for CO 2 + (A 2 Π u and B 2 Σ u + ) in the energy range of 17.2-19.0 eV: An experimental and theoretical study High resolution pulsed field ionization-photoelectron study of CO 2 + (X 2 Π g ) in the energy range of 13.6-14.7 eV J.Vacuum ultraviolet pulsed field ionization-photoelectron ͑PFI-PE͒ spectra for OCS have been obtained in the energy range 15.0-19.0 eV, covering the vibronic bands of OCS ϩ ͑A 2 ⌸, B 2 ⌺ ϩ , and C 2 ⌺ ϩ ͒. The ionization energies for the formation of the ground vibrational levels of OCS ϩ (A 2 ⌸ 3/2 , A 2 ⌸ 1/2 , B 2 ⌺ ϩ , and C 2 ⌺ ϩ ͒ from the ground OCS(X 1 ⌺ ϩ ) state have been determined as 15.0759Ϯ0.0005 eV, 15.0901Ϯ0.0005 eV, 16.0403Ϯ0.0005 eV, and 17.9552Ϯ0.0005 eV, respectively. We have also generated the theoretical adiabatic three dimensional potential energy functions ͑PEFs͒ for OCS ϩ (A 2 ⌸) by employing the complete active space self-consistent field and internally contracted multireference configuration interaction methods. Using these PEFs, the spectroscopic constants and low-lying rovibronic energy levels for OCS ϩ (A 2 ⌸) are calculated variationally. These calculations have made possible the identification of many PFI-PE vibronic bands for OCS ϩ (A 2 ⌸), which are originated from vibronic and Fermi resonance interactions. Owing to the different equilibrium geometries between the OCS ϩ (A 2 ⌸) and OCS(X 1 ⌺ ϩ ) states, the PFI-PE spectrum for OCS ϩ (A 2 ⌸) exhibits a long vibronic progression extending well above the OCS ϩ (B 2 ⌺ ϩ ) state. On the contrary, the PFI-PE spectra for OCS ϩ ͑B 2 ⌺ ϩ and C 2 ⌺ ϩ ͒ are overwhelmingly dominated by the ground ͑0,0,0͒ bands, exhibiting only weak vibrational progressions.

Vacuum Ultraviolet Pulsed Field Ionization−Photoelectron Study for N2O+ in the Energy Range of 16.3−21.0 eV

“…The energy step sizes used were in the range of 0.1−0.5 meV, and the counting times for each step varied in the range of 4−8 s. All PFI−PE spectra were calibrated before and after each experiment using the Ar + ( 2 P 3/2 ) and Ne + ( 2 P 3/2 ) PFI−PE bands obtained under the same experimental conditions. , The calibration scheme assumes that the Stark shifts of the IEs of N 2 O and rare gases are identical. Previous measurements indicate that the uncertainty of this calibration method is within ± 0.5 meV. − …”

“…The most attractive feature of the synchrotron radiation is its ease of tunability, making high-resolution PFI−PE measurement for many molecules in a large energy region a routine operation. Using the high-resolution synchrotron-based PFI−PE technique, we have obtained the rotationally resolved PFI−PE spectra for many diatomic molecules − and linear triatomic molecules CO 2 , − CS 2 , , and OCS. , …”

“…Using the high-resolution synchrotron-based PFI-PE technique, we have obtained the rotationally resolved PFI-PE spectra for many diatomic molecules [38][39][40] and linear triatomic molecules CO 2 , 41-43 CS 2 , 44,45 and OCS. 46,47 In this paper, we present a synchrotron-based PFI-PE study for N 2 O in the energy region of 16.3-21.0 eV, covering the ionization transitions from N 2 O(X 1 Σ + ) to valence ionic states…”

A vacuum ultraviolet pulsed field ionization-photoelectron study of cyanogen cation in the energy range of 13.2–15.9 eV

“…The accuracy of this energy calibration scheme is expected to be within ±0.5 meV based on previous works on similar molecular systems. [30][31][32][33][34][35][36][37][38] Table I lists the theoretical equilibrium geometry, rotational constants ͑B e , D e ͒, spin-orbit constant ͑A e,so ͒ and the variationally calculated anharmonic frequencies ͑ n , n = 1-5͒ of NCCN + ͑X 2 ⌸ g ͒ obtained at the RCCSD͑T͒ level of theory. The distances for the CN͑R 1,3 ͒ and CC͑R 2 ͒ bonds are predicted to be 1.192 Å and 1.343 Å, respectively.…”

O‐loss photodissociation of the OCS+ ion in the low‐lying electronic states studied using multiconfiguration second‐order perturbation theory

“…Numerous experimental studies have been devoted to the OCS + ion that had an old formula of COS + in the early literature. The experimental studies 3–25 all indicated that X 2 Π, A 2 Π, B 2 Σ + , and C 2 Σ + were the four lowest‐lying electronic states of the OCS + ion. In 2005, Chen et al 10 calculated the low‐lying electronic states of the OCS + ion using multiconfiguration second‐order perturbation theory.…”