Experimental determination of the ionization energy of IO(X{sup 2}/{Pi}{sub 3/2}) and estmations of {Delta}{sub f}H{degree}{sub 0}(IO{sup +}) and PA(IO)

Journal Article · Thu Jan 04 04:00:00 EST 1996 · Journal of Physical Chemistry

DOI:https://doi.org/10.1021/jp952405p· OSTI ID:196632

Zhang, Z; Kuo, S C; Klemm, R B ^[1]; Monks, P S; Stief, L ^[2]; Liebman, J F ^[3]; Huie, R E ^[4]

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1. Brookhaven National Lab., Upton, NY (United States)
2. NASA/Goddard Space Flight Center, Greenbelt, MD (United States)
3. Univ. of Maryland Baltimore County, MD (United States)
4. National Inst. of Standards and Technology, Gaithersburg, MD (United States)

Photoionization efficiency (PIE) spectra of IO(X{sup 2}{Pi}{sub i}) were measured over the wavelength range {Lambda} = 115.0-130.0 nm and in the ionization threshold region {Lambda} = 126.0-130.0 nm, using a discharge flow-photoionization mass spectrometer apparatus coupled to a synchrotron radiation source. Iodine oxide was generated by the reactions of O({sup 3}P) atoms with I{sub 2} and CF{sub 3}I. The PIE spectra displayed step-function behaviour. From the half-rise point of the initial step, a value of 9.73{sub 5}{+-}0.01{sub 7} eV was obtained for the adiabatic ionization energy (IE) of IO, corresponding to the IO{sup +}(X{sup 3}{Sigma}{sup -}) IMP IO(X{sup 2}{Pi}{sub 3/2}) transition. As this appears to be the first experimental determination of IE(IO), a trend analysis has been employed to provide further insight into the experimentally derived value. The separation between the first two steps in the PIE spectrum (which might be perturbed slightly due to autoionization) was used to derive the vibrational spacing of the cation, 1060{+-}160 cm{sup -1}. A Rydberg progression, presumably converging to the excited {sup 1}{Delta} state of the cation, has a convergence limit that lies 0.596 eV above the ground state of the cation. A selected value for the bond dissociation energy of IO leads to a value for the heat of formation of IO, from which estimates are made for the heat of formation of the iodine oxide cation and HOI and the proton affinity of IO. 54 refs., 3 figs., 3 tabs.

• OSTI ID: 196632
• Journal Information: Journal of Physical Chemistry, Journal Name: Journal of Physical Chemistry Journal Issue: 1 Vol. 100; ISSN JPCHAX; ISSN 0022-3654
• Country of Publication: United States
• Language: English

Related Subjects

40 CHEMISTRY
AFFINITY
DISSOCIATION ENERGY
ENERGY SPECTRA
EXCITED STATES
FORMATION HEAT
IODINE OXIDES
PHOTOIONIZATION
THERMODYNAMICS