Visible and ultraviolet resonance enhance multiphoton ionization photoelectron spectroscopy of H2S in the one-photon wavelength region 143–158 nm

Abstract

The Rydberg states of H2S have been investigated by multiphoton ionization, resonant enhanced at the two-photon and three-photon level (REMPI). The REMPI spectra (ion signal vs laser wavelength) are compared to the one-photon absorption spectrum. In addition, photoelectron spectra (PES) were collected at most of the absorption peaks in both the 2+1 and 3+1 REMPI processes. The vibrational state distribution of H2S+ formed by REMPI at a number of laser wavelengths is highly peaked at a single vibrational level. These intermediate Rydberg states could therefore be assigned on the basis of the PES. The REMPI-PES at other laser wavelengths were more complex probably because of perturbed intermediate Rydberg states. A comparison of the 2+1 and 3+1 REMPI wavelength scans shows significant peak intensity differences, which we attribute to the different Δl selection rules in the two- and three-photon absorption steps. New H2S 4p Rydberg states were observed in the two-photon resonance study, and a number of previously observed peaks have been reassigned on the basis of these results.

Photodissociation of hydrogen sulfide at 157.6 nm: Observation of SH bimodal rotational distribution

“…[16][17][18][19][20][21][22][23] Spectroscopy of the H 2 S molecule has also been studied quite extensively using absorption [24][25][26][27] and resonance-enhanced multiphoton ionization ͑REMPI͒ techniques. [28][29][30][31] The first UV absorption band of hydrogen sulfide peaks at ϳ195 nm. A progression of diffuse peaks is imposed upon the broad continuum of this transition, which extends to ϳ270 nm in the long wavelength direction and to ϳ160 nm in the short wavelength direction.…”

The Study of the Low-Lying Valence-Shell Excitations of Hydrogen Sulfide by Fast Electron Impact

“…Only two peaks at 7.85 and 8.04 eV were observed in the photoabsorption spectra and labeled as 4pb 2 1 A 2 (ν′ = 0) and 4pb 1 1 A 1 (ν′ = 0) states in ref . However, the assignments are reversed in refs and . Two extra peaks at 7.90 and 7.98 eV were observed by the REMPI experiments. , However, due to the lack of the transition at 7.85 eV in their works, they assigned the transition at 7.90 eV as the one previously observed at 7.85 eV.…”

“…The energy levels of H 2 S have been studied extensively by optical methods. ,− The valence-shell excited and Rydberg states have been assigned with the aid of the measurements by the photoabsorption , and the resonance enhance multiphoton ionization (REMPI) methods, − respectively. The photoabsorption cross sections or the equivalent optical oscillator strength densities in different wavelength regions ,,, have also been extensively investigated by the photoabsorption method.…”

Precision measurement of quasi-bound resonances in H$_2$ and the H + H scattering length

“…An excitation spectrum of the H 2 S molecule, probed via 2+1 UV resonance-enhanced multi-photon ionization is shown in Fig 3 . Two relatively strong and broad resonances, at excitation wavelengths between 276 and 292 nm, are observed in the H 2 S + ion channel, and are therefore associated with excited states in H 2 S. The sharp resonances, labeled with asterisks, are identified as strong S + ion signals from two-photon excitation of the S-atom, ( 4 S) 6p 5 P 1 , ( 2 D) 4p 1 P 1 , ( 2 D) 4p 3 D 1 and ( 2 D) 4p 1 F 3 -3p 4 1 D 2 [48]. Production and precision spectroscopy of S atoms resulting from H 2 S photolysis was investigated previously in our setup under similar conditions [49].…”

“…The strongest two resonances peaking at excitation energies of 68700 cm −1 and 70900 cm −1 are assigned as two-photon excitation to 4p 1 B 1 (100) and 3d 1 B 2 , respectively. Processes related to the first level have been discussed extensively by Steadman et al [48]. The latter level is based on assignments in the absorption spectrum of Masuko et al [50].…”