Dynamic Stark shift of the R-3(1) Rydberg state of CH3I (original) (raw)
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Molecular Rydberg transitions. Multichannel approaches to electronic states: CH3I
Physical Review A, 1981
A multichannel quantum-defect theoretic (MQDT) analysis of the high-resolution vacuum-ultraviolet spectrum of CH3I in the energetic region below the first ionization limit is presented. The analysis is based upon, and substantiates a posteriori, quantumdefect analogies between Xe and CH3I: that is, only purely electronic molecular channels are allowed to interact. A new d series converging on the first ionization limit is assigned as a result of the MQDT analysis.
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.
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.
The Stark effect in Rydberg states of a highly polar diatomic molecule: CaF
The Journal of Chemical Physics, 2009
The Stark effect in molecular Rydberg states is qualitatively different from the Stark effect in atomic Rydberg states because of the anisotropy of the ion core and the existence of rotational and vibrational degrees of freedom. These uniquely molecular features cause the electric-field-induced decoupling of the Rydberg electron from the body frame to proceed in several stages in a molecule. Because the transition dipole moment among the same-n * Rydberg states is much larger than the permanent dipole moment of the ion core, the decoupling of the Rydberg electron from the ion core proceeds gradually. In the first stage, analyzed in detail in this paper, ᐉ and N are mixed by the external electric field, while N + is conserved. In the further stages, as the external electric field increases, N + , n * , and v + are expected to undergo mixing. We have characterized these stages in n * = 13, v + = 1 states of CaF. The large permanent dipole moment of CaF + makes CaF qualitatively different from the other molecules in which the Stark effect in Rydberg states has been described ͑H 2 , Na 2 , Li 2 , NO, and H 3 ͒ and makes it an ideal testbed for documenting the competition between the external and CaF + dipole electric fields. We use the weak-field Stark effect to gain access to the lowest-N rotational levels of f, g, and h states and to assign their actual or nominal N + quantum number. Lowest-N rotational levels provide information needed to disentangle the short-range and long-range interactions between the Rydberg electron and the ion core. We diagonalize an effective Hamiltonian matrix to determine the ᐉ-characters of the 3 ഛ ᐉ ഛ 5 core-nonpenetrating 2 ⌺ + states and to characterize their mixing with the core-penetrating states. We conclude that the mixing of the ᐉ =4, N − N + =−4͑g͑−4͒͒ state with lower-ᐉ 2 ⌺ + states is stronger than documented in our previous multichannel quantum defect theory and long-range fits to zero-field spectra.
Dynamics of Very High Molecular Rydberg States: The Intramolecular Processes
1994
Classical trajectory computations are used to document and examine the purely intramolecular decay dynamics of very high Rydberg states of an isolated cold molecule. The Hamiltonian is that of an anisotropic ionic core about which the Rydberg electron revolves. The equations of motion are integrated using action angle variables in order to ensure numerical stability for many orbits of the electron. Examination of individual trajectories verifies that both "up" and "down" intramolecular processes are possible. In these, the electron escapes from the detection window by a gain or loss of enough energy. Either process occurs in a diffusive like fashion of many smaller steps, except for a very small fraction of prompt processes. The results for ensembles of trajectories are examined in terms of power spectra of the different modes of motion and in terms of the decay kinetics.
Journal of Molecular Spectroscopy, 1981
The electronic absorption spectrum of cyanogen chloride has been investigated in the range 2200-1250 A. The first s-Rydberg transitions, .%'Z'-* %, and B'Z' + 'II, have been assigned, and analyzed to yield exchange and spin-orbit coupling parameters. The relative intensities of these two transitions have been shown to accord with an intermediate coupling situation. The P + ?y* intravalence excitations, leading to '.VY-, A and 2') states, have been discussed. It has been shown that one or both of the 'I-and 'A states have bent geometries and that the IX+ state is located (tentatively) at 79 755 cm-'. Two o + r*/r + CT* states have been assigned, one at 56 340 cm-', the other at 74 450 cm-'. The latter assignment is tentative, being largely based on observed vibronic interferences between the X'I' + 'II, transition and the 74 450 cm-' transition. A considerable amount of vibrational oscillator strength and quantum defect data is presented.
Vacuum–ultraviolet photodissociation of C2H2 via Rydberg states: a study of the fluorescent pathways
Chemical Physics Letters, 1999
The visible fluorescence produced by vacuum-ultraviolet photodissociation of acetylene, particularly through the Rydberg states, has been studied in a gas-flow system using synchrotron radiation as a light source between 154 and 60 nm and an original light collection device. Excitation of the Rydberg states below the first IP reveals only the C H product by 2ĩ ts A-X continuum emission spectrum between 330 and 900 nm. Evolution in the emission spectral profile as a function of excitation wavelength has been observed, indicative of specific internal distribution favoring the bending levels of the à 2 state of C H. A new assignment of the Rydberg series converging to the first excited state A A of the cation is proposed 2 g on the basis of recent experimental and theoretical characterization of this state and leads to an approximate value of the Ž y1 . C-C stretching frequency of the cation n f 1500 cm . q