Coherent Laser Control of the Product Distribution Obtained in the Photoexcitation of HI

Active control of the distribution of products of a chemical reaction was demonstrated by using a method based on the principle of quantum mechanical interference. Hydrogen iodide (HI) molecules were simultaneously excited above their ionization threshold by two competing pathways. These paths were absorption of three ultraviolet photons of frequency ω1 and one vacuum ultraviolet photon of frequency ω3 = 3ω1. The HI+ and I+ signals were modulated as the phase between the lasers was varied, with the HI+ signal lagging by 150° ± 15°. A mechanism consisting of autoionization and predissociation is proposed.

[1]  Robert J. Gordon,et al.  Coherent phase control of the photoionization of H2S , 1995 .

[2]  S. Rice,et al.  New ideas for guiding the evolution of a quantum system. , 1992, Science.

[3]  M. Shapiro,et al.  Coherent radiative control of IBr photodissociation via simultaneous (ω1,ω3) excitation , 1991 .

[4]  S. Pratt.  Zero kinetic energy, pulsed‐field ionization spectroscopy of hydrogen iodide , 1994 .

[5]  U. Heinzmann,et al.  Observation of vibrational excitation in photoelectron spectroscopy of HI+ 2Π , 1992 .

[6]  J. Berkowitz,et al.  Photoionization of atomic iodine and atomic tellurium , 1981 .

[7]  Chen,et al.  Measurements of optical phase variations using interfering multiphoton ionization processes. , 1990, Physical review letters.

[8]  Paul Brumer,et al.  Laser control of product quantum state populations in unimolecular reactions , 1986 .

[9]  Yin,et al.  Interference between optical transitions. , 1990, Physical review letters.

[10]  Ashok Kumar,et al.  The use of coherent phase control of multiphoton ionization to measure the refractive indices of H2 and Ar between 1100 and 1150 Å , 1993 .

[11]  Nakajima,et al.  Effects of the phase of a laser field on autoionization. , 1994, Physical review. A, Atomic, molecular, and optical physics.

[12]  S. G. Tilford,et al.  Electronic spectra and structure of the hydrogen halides the b 3Πi and C 1Π states of HI and DI , 1970 .

[13]  E. Grant,et al.  Two-pathway coherent control of photoelectron angular distributions in molecular NO , 1995 .

[14]  M. Shapiro,et al.  Theory of electronic branching in the photodissociation of HI and DI , 1988 .

[15]  C. J. Zietkiewicz,et al.  Photoelectron spectroscopy of the multiphoton ionization and above threshold ionization of HI at 532 and 355 nm , 1994 .

[16]  Nakajima,et al.  Manipulation of the line shape and final products of autoionization through the phase of the electric fields. , 1993, Physical review letters.

[17]  J. Hepburn,et al.  Vacuum ultraviolet laser photoionization spectroscopy: A high-resolution study of spin-orbit autoionization in HI , 1989 .

[18]  J. Eland,et al.  Photoionization mass spectrometry of HI and DI at high resolution , 1977 .

[19]  A. Bandrauk,et al.  Laser control of photopredissociation angular distributions and photoionization in Cl2 by two color interference , 1994 .

[20]  S. Park,et al.  Coherent laser control of bound‐to‐bound transitions of HCl and CO , 1992 .

[21]  Herschel Rabitz,et al.  Coherent Control of Quantum Dynamics: The Dream Is Alive , 1993, Science.

[22]  G. Bjorklund,et al.  Effects of focusing on third-order nonlinear processes in isotropic media. [laser beam interactions , 1975 .

[23]  Nakajima,et al.  Modulating ionization through phase control. , 1992, Physical review. A, Atomic, molecular, and optical physics.

[24]  Robert J. Gordon,et al.  Coherent laser control of the resonance‐enhanced multiphoton ionization of HCl , 1991 .

[25]  Gerber,et al.  Femtosecond time-resolved molecular multiphoton ionization: The Na2 system. , 1991, Physical review letters.

[26]  A. E. Vries,et al.  Photofragmentation of HI in the first continuum , 1983 .

[27]  Smith,et al.  Asymmetric photoelectron angular distributions from interfering photoionization processes. , 1992, Physical review letters.

[28]  P. Bucksbaum,et al.  Above-threshold ionisation with a two-colour laser field , 1990 .

[29]  Samuel H. Tersigni,et al.  Wavepacket dancing: Achieving chemical selectivity by shaping light pulses , 1989 .