Photoionization mass spectrometric studies of AsH/sub n/ (n = 1--3)
The photoion yield curves of the free radicals AsH and AsH/sub 2/, prepared by the reaction of H atoms with AsH/sub 3/, have been measured. The adiabatic ionization potential of AsH (forming AsH/sup +/, X /sup 2/Pi/sub 1//sub ///sub 2/) is 9.641 +- 0.008 eV. Autoionizing Rydberg states are observed and analyzed to converge to an a /sup 4//Sigma//sup -/ state lying 1.94 eV higher in energy. The adiabatic ionization potential of AsH/sub 2/ (forming AsH/sup +//sub 2/, X /sup 1/A/sub 1/) is 9.443 +- 0.007 eV. The /sup 3/B/sub 1/ state of AsH/sup +//sub 2/ is conservatively estimated from the spectrum to lie 0.60--1.46 eV higher in energy, with the lower figure expected to be close to the true value. In addition, the ion yield curves of AsH/sup +//sub 3/, AsH/sup +//sub 2/, and AsH/sup +/ from photoionization of AsH/sub 3/ have been measured. From these measurements, the adiabatic ionization potential of AsH/sub 3/ is 9.82 +- 0.01 eV, the appearance potential of AsH/sup +//sub 2/ (+H) is 12.69 +- 0.01 eV, and that of AsH/sup +/(+H/sub 2/) is 11.295 +- 0.05 eV. The latter two measurements, when combined with the corresponding ionization potentials, yield D/sub 0/(H/sub 2/As--H) = 74.9 +- 0.2 kcal/mol and D/sub 0/(HAs--H) = 66.5 +- 0.2 kcal/mol. The value of D/sub 0/(As--H), as deduced from these measurements, depends upon an accurate heat of atomization of AsH/sub 3/, which in turn requires an accurate value for /Delta//sup circle-open//sub f//sub =/ (As,g). An analysis of alternative values is presented, from which D/sub 0/(As--H) = 64.6 +- 0.7 kcal/mol (2.80 +- 0.03 eV) is obtained.
- Research Organization:
- Chemistry Division, Argonne National Laboratory, Argonne, Illinois 60439
- OSTI ID:
- 6726683
- Journal Information:
- J. Chem. Phys.; (United States), Journal Name: J. Chem. Phys.; (United States) Vol. 89:12; ISSN JCPSA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
400500* -- Photochemistry
ARSENIC COMPOUNDS
ARSENIC HYDRIDES
CHARGED PARTICLES
DATA
DISSOCIATION HEAT
ENTHALPY
EXPERIMENTAL DATA
HYDRIDES
HYDROGEN COMPOUNDS
INFORMATION
IONIZATION
IONIZATION POTENTIAL
IONS
MASS SPECTROSCOPY
MOLECULAR IONS
NUMERICAL DATA
PHOTOIONIZATION
PHYSICAL PROPERTIES
RADICALS
REACTION HEAT
SPECTROSCOPY
THERMODYNAMIC PROPERTIES
YIELDS