Predissociation and autoionization of triplet Rydberg states in molecular hydrogen.

We present single-photon spectroscopy in molecular hydrogen starting from the metastable c3Piu- state to a number of triplet nd-Rydberg states (v = 0 - 4, n = 12 - 20). Using fast beam spectroscopy both the autoionization channel and the predissociation channel are quantified, field free, as well as with small electric fields. Coupling with the i3Pig state is assumed to be responsible for field-free predissociation of the v = 0 Rydberg levels. The stronger observed predissociation channel of the v = 1 Rydberg levels is due to the nonadiabatic interaction with the h3Sigmag+ state in combination with l mixing due to an external electric field. No direct evidence is found for possible electric field induced predissociation of the gerade Rydberg states by low lying ungerade states. The competition between autoionization and predissociation is discussed in terms of possible consequences for dissociative recombination involving low energy electron collisions with the H2+ molecular ion.

[1]  V. Ngassam,et al.  H2 triplet states contribution to low-energy dissociative recombination of H2+ , 2003 .

[2]  H. Offerhaus,et al.  Application of a time-resolved event counting technique in velocity map imaging , 2002 .

[3]  A. Matzkin,et al.  Multichannel-quantum-defect-theory treatment of preionized and predissociated triplet gerade levels of H 2 , 2000 .

[4]  A. Osterwalder,et al.  Measurement of the hyperfine structure in low-l, high-n Rydberg states of ortho H2 by millimeter wave spectroscopy , 2000 .

[5]  D. Strasser,et al.  An innovative approach to multiparticle three-dimensional imaging , 2000, 2000 IEEE Nuclear Science Symposium. Conference Record (Cat. No.00CH37149).

[6]  L. Wolniewicz.  Adiabatic Potentials of the Lowest in 1Πg and 1,3Δg States of the Hydrogen Molecule , 1995 .

[7]  J. Tennyson,et al.  Dissociative recombination without curve crossing: study of HeH+ , 1994 .

[8]  Ross,et al.  Multichannel quantum-defect theory of double-minimum 1 Sigma g+ states in H2. I. Potential-energy curves. , 1994, Physical review. A, Atomic, molecular, and optical physics.

[9]  H. Takagi.  Rotational effects in the dissociative recombination process of H2++e , 1993 .

[10]  W. Glab,et al.  Dissociation and ionization of vibrationally autoionizing Rydberg states of H2 in a static electric field , 1993 .

[11]  Qin,et al.  Stark effect and rotational-series interactions on high Rydberg states of molecular hydrogen. , 1993, Physical review. A, Atomic, molecular, and optical physics.

[12]  J. Mitchell,et al.  Dissociative Recombination : Theory, Experiment, and Applications , 1993 .

[13]  Fu,et al.  Determination of the hyperfine structure of H2+( nu =0, R=1) by microwave spectroscopy of high-L n=27 Rydberg states of H2. , 1992, Physical review. A, Atomic, molecular, and optical physics.

[14]  K. Welge,et al.  Singlet gerade Rydberg states of molecular hydrogen , 1992 .

[15]  Hessels,et al.  Microwave spectroscopy of the high-L H2 Rydberg states ( nu =0, R=1) n=10 G, H, I, and K. , 1991, Physical review. A, Atomic, molecular, and optical physics.

[16]  J. Rychlewski,et al.  Adiabatic potential energy curves for the b and e3Σu+ states of the hydrogen molecule , 1990 .

[17]  Lindsay,et al.  Autoionization rates and energy levels of triplet nf, v=1 Rydberg states of H2. , 1990, Physical review. A, Atomic, molecular, and optical physics.

[18]  D. Huestis,et al.  Spectroscopic study of the second 3Πg state of H2 : A bound triplet state perturbed by a doubly excited state , 1990 .

[19]  Helm,et al.  Autoionization of H2 induced by a doubly excited triplet state. , 1988, Physical review letters.

[20]  Ross,et al.  Quantum-defect theory of double-minimum states in H2. , 1987, Physical review letters.

[21]  Short,et al.  Precision spectroscopy of the nf triplet Rydberg states of H2 and determination of the triplet ionization potential. , 1986, Physical review letters.

[22]  Helm,et al.  Autoionizing Rydberg states in triplet molecular hydrogen. , 1985, Physical review letters.

[23]  Knight,et al.  Observation of triplet nd autoionizing Rydberg states in H2. , 1985, Physical review letters.

[24]  H. Helm,et al.  Fast neutral-beam photofragment spectroscopy of H/sub 2/ c /sup 3/Pi/sub u//sup -/ , 1984 .

[25]  J. Bardsley,et al.  Dissociative recombination in low-energy e-H/sub 2//sup +/ collisions , 1983 .

[26]  F. Pipkin,et al.  Triplet 4 d states of H 2 : Experimental observation and comparison with an ab initio model for Rydberg-state energies , 1983 .

[27]  S. Guberman.  The doubly excited autoionizing states of H2 , 1983 .

[28]  F. Pipkin,et al.  Observation of the 4s3Σ+g state of H2 , 1982 .

[29]  J. Los,et al.  Time and position‐sensitive detector for dissociative processes in fast beams , 1982 .

[30]  A. Giusti.  A multichannel quantum defect approach to dissociative recombination , 1980 .

[31]  G. Herzberg,et al.  Constants of diatomic molecules , 1979 .

[32]  D. Auerbach,et al.  Merged electron-ion beam experiments. I. Method and measurements of (e-H2+) and (e-H3+) dissociative-recombination cross sections , 1977 .

[33]  R. Freund,et al.  Singlet‐triplet anticrossings in H2 , 1974 .

[34]  G. Dieke.  The hydrogen molecule wavelength tables of Gerhard Heinrich Dieke , 1972 .

[35]  J. Bardsley.  Configuration interaction in the continuum states of molecules , 1968 .