Minimum energy geometries, harmonic vibrational frequencies, and stepwise binding energies have been obtained for the cluster ions NO + ‚(H 2 O) n , n ) 1-4. From systematic ab initio calculations on the lighter NO + ‚(H 2 O) n complexes (n ) 1-2) at MPn, CCSD, and CCSD(T) levels of electron correlation with different basis sets, it was found that the MP2/6-311++G(2d,p) level of theory was reliable for the calculation of minimum-energy geometries and harmonic vibrational frequencies. Relative electronic energies were evaluated at the MP2/aug-cc-pVTZ//MP2/6-311++G(2d,p) level. The inclusion of zero point energy (ZPE) corrections, as well as counterpoise corrections for basis set superposition errors (BSSE), in the calculation of binding energies was essential to obtain the correct energy ordering for the different isomers of a cluster ion. The nature of the stepwise hydration processes was discussed based on the isomeric structures obtained. A reaction route for nitrous acid (HONO) formation when a water molecule is added to NO + ‚(H 2 O) 3 has been established.

He I photoelectron spectra have been recorded for the F + C 2 H 5 OH reaction, and a band has been identified associated with the primary reaction product CH 3 CHOH. The first adiabatic and vertical ionization energies of this radical have been measured as (6.64 ( 0.03) and ( 7.29 ( 0.03) eV respectively. The assignment of this band to CH 3 CHOH is supported by ab initio calculations performed at the G2 level of theory. Spectra recorded at different reaction times have demonstrated the short-lived nature of CH 3 CHOH and the major pathway of the F + C 2 H 5 OH reaction. The value measured for the adiabatic ionization energy has allowed the heat of formation of CH 3 CHOH to be derived from the heat of formation of CH 3 CHOH + .

The thermal decomposition of 2-H-heptafluoropropane, CF(3)CHFCF(3), at low pressure, heavily diluted in argon, has been studied over the temperature range 600-2000 degrees C using photoelectron spectroscopy. Comparison of the results obtained has been made with results of recent electronic structure calculations of possible decomposition pathways and results of a shock tube study. The most favored reaction thermodynamically, to produce CF(3)CF=CF(2) + HF, is found to be the main decomposition reaction at lower temperatures, 600-900 degrees C. At higher temperatures, 900-1200 degrees C, the decomposition reaction to give C(2)F(4) + CF(3)H was found to become important. No evidence for CF(3)CHFCF(3) --> CF(3)CHF + CF(3), a reaction expected to be important from a shock tube study, performed at much higher pressures, or for CF(3)CHFCF(3) --> CF(3)CF + CF(3)H was obtained, although for the latter reaction it is likely that CF(3)CF converts into C(2)F(4) under the conditions used before photoionization, in the ionization region of the photoelectron spectrometer. At higher temperatures C(3)F(6) decomposes to C(2)F(4) + CF(2), and C(2)F(4) decomposes to CF(2). Ab initio calculations have been performed of the adiabatic and vertical ionization energies of possible primary pyrolysis products to assist assignment of the photoelectron spectra recorded for heated flowing gas samples. A comparison is made between the threshold photoelectron spectrum and the photoelectron spectrum of CF(3)CF=CF(2).