Vibrationally structured electronic transitions of N2O+ndash;Ar have been observed by measuring the wavelengthhyphen;dependent yields of the photodissociation reactions to yield N2O+or Ar+. There appear to be four structured overlapping electronic band systems which are distinguished by vibrational spacings and by their propensity towards production of either N2O+or Ar+. Variations in the Ar+/N2O+photoproduct ratio with wavelength are explained as due to vibrational predissociation on different potentialhyphen;energy surfaces correlating with either Ar+or N2O+products. The first band system, observed exclusively at the N2O mass, has its origin close to 445 nm, corresponding approximately to the difference in the energies of N2O+lsqb;Xthinsp;2Pgr;3/2rsqb;+Arlsqb;1S0rsqb; and N2Olsqb;1Sgr;+rsqb;+Ar+lsqb;2P3/2rsqb; and is assigned as an intracluster chargehyphen;transfer transition. Two strong band systems situated to higher energy are assigned as transitions to the two additional electronic states which are expected to correlate with2P3/2and2P1/2Ar+and N2Olsqb;1Sgr;+rsqb; products. While excitation of these two bands results almost exclusively in Ar+production, a fourth weaker band near 342 nm leads to N2O+and appears likely to be a transition to a state correlating with an excited vibronic state of N2O+lsqb;Athinsp;2Sgr;+(1,0,0)rsqb;+Arlsqb;1S0rsqb;. The different band systems exhibit extensive vibrational progressions involving the deformation of the bond between the N2O and the Ar. The shift in the onset of the first charge transfer from the difference in the Ar and N2O ionization potentials combined with the appearance energy for Ar+production allow tentative estimates of 690 and 1340 cmminus;1to be made for the dissociation energies of the lowest and first excited states of N2O+ndash;Ar.
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