Halfcollision studies of singlettotriplet energy transfer: Action spectroscopy and predissociation dynamics of electronically excited CdH2 and CdD2 complexes J. Chem. Phys. 97, 3135 (1992); 10.1063/1.463001 Reinvestigation of vibronic level dependence of fluorescence quantum yields and radiative and nonradiative lifetimes of pdifluorobenzene in its first excited singlet state (1 B 2u ) J. Chem. Phys. 67, 236 (1977); 10.1063/1.434548Spectroscopic studies on naphthalene in the vapor phase. II. Fluorescence quantum yields from single vibronic levels in the first excited singlet state-behavior of higher excited singlet states

Despite the tremendous advances in laser cooling of neutral atoms and positive ions, no negatively charged ion has been directly laser cooled. The negative ion of lanthanum, La(-), has been proposed as the best candidate for laser cooling of any atomic anion [ and , Phys. Rev. A 81, 032503 (2010)]. Tunable infrared laser photodetachment spectroscopy is used to measure the bound-state structure of La(-), revealing a spectrum of unprecedented richness with multiple bound-bound electric dipole transitions. The potential laser-cooling transition ((3)F(2)(e)→(3)D(1)(o)) is identified and its excitation energy is measured. The results confirm that La^{-} is a very promising negative ion for laser-cooling applications.

The experimental study of molecular dissociation of H2+ by intense laser pulses is complicated by the fact that the ions are initially produced in a wide range of vibrational states, each of which responds differently to the laser field. An electrostatic storage device has been used to radiatively cool HD+ ions enabling the observation of above threshold dissociation from the ground vibrational state by 40 fs laser pulses at 800 nm. At the highest intensities used, dissociation through the absorption of at least four photons is found to be the dominant process.

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Articles you may be interested inA femtosecond velocity map imaging study on B-band predissociation in CH3I. II. The 2 0 1 and 3 0 1 vibronic levels High-resolution millimeter wave spectroscopy and multichannel quantum defect theory of the hyperfine structure in high Rydberg states of molecular hydrogen H 2 Photofragment spectroscopy is applied to investigate perturbations in the photoexcitation and predissociation of excited singlet states of N 2 . Discrete rovibrational levels in the Rydberg states cЈ 1 ͚ u ϩ (vϭ3 and 4͒ and c 1 ͟ u (vϭ3 and 4͒ and in the valence state bЈ 1 ͚ u ϩ (vϭ10, 12, 13, and 15͒ are prepared by laser excitation from the metastable aЉ 1 ͚ g ϩ (vϭ0) state in a fast ͑3 keV͒ molecular beam. Fragment atoms produced by predissociation are monitored as a function of exciting laser frequency using a position-and time-sensitive detector to measure the photofragment intensity distribution in the rovibrational bands. The photofragment spectra show extreme departures from normal rovibronic intensity distributions due to strong perturbations in the two highly mixed complexes: cЈ(3)/c(3)/bЈ(10) and cЈ(4)/c(4)/bЈ(13). The measured photofragment intensities are compared to photoexcitation line strengths calculated using a comprehensive model of the Rydberg-valence state mixing ͓Stahel, Leoni, and Dressler, J. Chem. Phys. 79, 2541 ͑1983͔͒. This theoretical model accurately predicts most of the variations in the photofragment intensities, and reveals the causes of the perturbations. For the states investigated in the present study, the primary factor that determines the photofragment intensity is the degree of bЈ character of the state, which favorably affects both photoexcitation and predissociation. Interference effects are found to be important in determining absorption intensities in N 2 .

K-shell photodetachment from C Ϫ has been investigated in the photon energy range between 280 and 285 eV using the merged ion-beam-photon-beam technique. C Ϫ ions were produced using a Cs sputtering negative-ion source, while the photons were produced by the undulator beam line 10.0.1 of the Advanced Light Source. C ϩ ions formed by double detachment were detected as a function of incident photon energy. Using this collinear arrangement, the relative cross sections were measured and compared with theoretical predictions. The measured spectrum shows the first experimental evidence of the 1s2s 2 2p 4 ( 4 P) shape resonance near 281.7 eV, which is in excellent agreement with two independent R-matrix calculations for the 1s photodetachment cross section of C Ϫ producing C ϩ .

We report on the first experimental observation of a new threshold behavior observed in the 5(2)G partial channel in photodetachment of K(-). It arises from the repulsive polarization interaction between the detached electron and the residual K(5(2)G) atom, which has a large negative dipole polarizability. In order to account for the observation in the K(5(2)G) channel, we have developed a semiclassical model that predicts an exponential energy dependence for the cross section. The measurements were made with collinear laser-ion beams and a resonance ionization detection scheme.