Vibrational autoionization of state-selective jet-cooled methanethiol (CH3SH) investigated with infrared + vacuum-ultraviolet photoionization (original) (raw)
Related papers
Tm autoionization rydberg states in the vicinity of the third and fourth atomic ionization limit
Zeitschrift f�r Physik D: Atoms, Molecules and Clusters, 1989
The energies of about 200 autoionization Rydberg states of the thulium atom have been measured in the 57380-58960cm -1 energy region by laser multistep excitation and subsequent autoionization with an accuracy of +0.4 c m -i . More than a half of the states have been grouped in series. New spectroscopic information has been derived. Three-step two-colour effective excitation schemes have been proposed for thulium atom detection.
Zeitschrift f�r Physik D Atoms, Molecules and Clusters, 1987
The energies of 190 Rydberg and autoionization 4 f 13 6snp-states of the Tm atom (ground electron configuration 4 f ~3 6s 2, nuclear charge Z=69) have been measured by the laser multistep excitation with subsequent electric field ionization method. The investigation range of these states has been extended towards states with higher and lower values of the principal quantum number. As a result the energies of 160 states have been obtained for the first time. The experiment has been carried out on an automated laser photoionization spectrometer. The measurement accuracy has been _ 0.5 cm-~
Preparation and characterization of long-lived molecular Rydberg states: Application to HD
The Journal of Chemical Physics, 1996
The decay dynamics by predissociation and rotational autoionization of high Rydberg states of HD close to the first few rotational levels of the ground vibronic state of the HD ϩ cation have been studied by delayed pulsed field ionization following resonant ͑1ϩ1Ј͒ two-photon absorption via the B state. Although predissociation and autoionization both contribute to the rapid decay of Rydberg states with principal quantum number nӶ100, the highest Rydberg states ͑nϾ100͒ are stable for more than 20 s. In contrast to H 2 , channels associated with an HD ϩ ͑v ϩ ϭ0, N ϩ ϭeven͒ ion core are coupled to channels associated with an HD ϩ ͑v ϩ ϭ0, N ϩ ϭodd͒ ion core. We demonstrate that complex resonances that arise from rotational channel interactions between low ͑nϳ25͒ Rydberg states characterized by a core with rotational angular momentum quantum number N ϩ ϩ2 and the pseudocontinuum of very high Rydberg states characterized by an N ϩ core can be used with high efficiency to produce long-lived high Rydberg states. An investigation of the pulsed field ionization characteristics of these complex resonances enables us to measure the branching between diabatic and adiabatic field ionization and to determine the optimal conditions required to extend the method of H-photofragment Rydberg translational spectroscopy pioneered by Schnieder et al. ͓J. Chem. Phys. 92, 7027 ͑1990͔͒ to molecular species.
Chemical Physics, 1991
The photoionization efficiency curves of NH 3 and its three isotopomers have been investigated in the photon energy range of the first ionized state. From the analysis of the corresponding vibrational structure, wavenumbers (ω e ) and anharmonicity constants (ω e x e ) are deduced. The detailed investigation of the abundant autoionization structure tends to show the adiabatic ionization energy to be 10.072 ± 0.010 eV for NH 3 , NH 2 D and NHD 2 and 10.083 ± 0.010 eV for ND 3 . All autoionization features were classified in vibrational progressions (v 2 bending mode) belonging to nsa 1 (or nd) and npe (n=5, 6, 7) Rydberg series. Vibrational autoionization occurs through ∆v transitions up to -9. A qualitative analysis of the intensity distribution of these series strongly supports that transitions involving odd ∆v values are favoured. This observation can be understood by applying group theoretical considerations to the theory of vibrational autoionization. dispersed by a 1 meter NIM-monochromator (McPherson 225) equipped with a 1200 l /mm grating. The entrance and exit slits were set to give a resolution of about 0.2 nm. The absolute calibration of the wavelength was better than ±0.2 nm.
Spectrochimica Acta Part B: Atomic Spectroscopy, 1997
The temporal behavior of the laser enhanced ionization signal of mercury was studied in a quartz cell under low buffer gas pressure. Using fast electronics and a short (34 ns) laser pulse, it was possible to distinguish, in one single time-resolved ionization waveform, the non-selective photoionization component of the signal from that which was due to collisional ionization from selected levels. Experimental results were shown to agree with those obtained by computer simulation, and optimal conditions for deconvolution of the two components were studied. © 1997 Elsevier Science B.V.
The Journal of Chemical Physics, 2008
The photoionization efficiency ͑PIE͒ spectra of metastable sulfur ͑S͒ atoms in the 1 D and 1 S states have been recorded in the 73 350-84 950 cm −1 frequency range by using a velocity-mapped ion imaging apparatus that uses a tunable vacuum ultraviolet laser as the ionization source. The S͑ 1 D͒ and S͑ 1 S͒ atoms are produced by the 193 nm photodissociation of CS 2. The observed PIE spectra of S͑ 1 D͒ and S͑ 1 S͒ shows 35 autoionizing resonances with little or no contribution from direct photoionization into the S + ͑ 4 S 3/2 ͒ + e − ionization continuum. Velocity-mapped ion images of the S + at the individual autoionizing Rydberg resonances are used to distinguish whether the lower state of the resonance originates from the 1 D, 1 S, or 3 P states. The analysis and assignment of the Rydberg peaks revealed 22 new Rydberg states that were not previously known. The autoionization lifetimes of the Rydberg states are derived from the linewidths by fitting the lines with the Fano formula. Deviations from the scaling law of ͑n * ͒ ϰ n *3 , where n * is the effective quantum number of the Rydberg state, are observed. This observation is ascribed to perturbations by nearby triplet Rydberg states, which shorten the autoionization lifetimes of the singlet Rydberg levels.
Chemical Physics Letters, 1999
Mass-analyzed threshold ionization experiments have enabled mapping of the n-dependent Rydberg state survival probability for a series of molecules. Utilizing vacuum ultraviolet photons, one-photon Rydberg manifold spectra of Ar, HCl, N , C H and O were produced, and the prospects of photoinduced Rydberg ionization experiments examined. It was 2 6 6 2 found that the widths of Rydberg manifolds for the molecules studied are quite different. Hydrogen chloride and nitrogen have the narrowest manifold width, followed by benzene, and then oxygen. These varying widths are most strongly Ž. correlated with the angular momentum i.e., quantum defect of the initially prepared Rydberg orbital.
Observation of the Stark effect in autoionising Rydberg states of molecular hydrogen
Chemical Physics Letters, 1991
The dc Stark effect is studied for autoionising Rydberg states of H 2 converging on the ν +=2 ionisation limit. The levels ( n = 13-22) are excited from the ground state using a coherent XUV source (bandwidth ≈ 1 cm -1) and are strongly perturbed by the field (15-2000 V/cm). Many new states are observed, including the high-/hydrogenic manifolds. A detailed Stark map is obtained for the first time, and a matrix diagonalisation calculation of field-induced state mixing is carried out to explain some of the observed features.
Time-resolved photoionization spectroscopy of mixed Rydberg-valence states: indole case study
Time-resolved photoelectron imaging was used to study non-adiabatic relaxation dynamics in gas-phase indole following photo-excitation at 267 nm and 258 nm. Our data analysis was supported by various ab initio calculations using both coupled cluster and density functional methods. The highly differential energy-and angle-resolved information provided by our experimental approach provides extremely subtle details of the complex interactions occurring between several low-lying electronically excited states. In particular, new insight into the role and fate of the mixed Rydberg-valence 3s/ps* state is revealed. This includes population residing on the excited state surface at large N–H separations for a relatively long period of time (B1 ps) prior to dissociation and/or internal conversion. Our findings may, in part, be rationalized by considering the rapid evolution of this state's electronic character as the N–H stretching coordinate is extended – as extensively demonstrated in the supporting theory. Overall, our findings highlight a number of important general caveats regarding the nature of mixed Rydberg-valence excited states, their spectral signatures and detection sensitivity in photoionization measurements, and the evaluation of their overall importance in mediating electronic relaxation in a wide range of small model-chromophore systems providing bio-molecular analogues – a topic of considerable interest within the chemical dynamics community over the last decade.