Photoelectron spectroscopy of HNOminus;and DNOminus;

摘要

We have obtained the photoelectron spectra of HNOminus;and DNOminus;using a recently constructed negative ion photoelectron spectrometer. We observe detachment to three different electronic states of HNO and DNO, namely theXtilde;thinsp;1Aprime;,atilde;thinsp;3Aprime;prime;, andAtilde;thinsp;1Aprime;prime; states. The electron affinity of HNO is determined to be 0.338plusmn;0.015 eV while that of DNO is 0.330plusmn;0.015 eV. Theatilde;thinsp;3Aprime;prime; state, which has not been observed directly before, is found to lie 0.778plusmn;0.020 eV above theXtilde;thinsp;1Aprime; state in HNO and 0.785plusmn;0.020 eV in DNO. We see vibrational excitation up to ngr;prime;2=3 of the ngr;2(Nndash;O stretch) mode in the HNO and DNOXtilde;thinsp;1Aprime; state. In theatilde;thinsp;3Aprime;prime; andAtilde;1Aprime;prime; states, we see excitation of both ngr;2and ngr;3(Hndash;Nndash;O bend) modes. The fundamental frequencies for theatilde;thinsp;3Aprime;prime; state are ngr;2=1468plusmn;140 cmminus;1and ngr;3=992plusmn;150 cmminus;1for HNO and ngr;2= 1452plusmn;140 cmminus;1and ngr;3=750plusmn;140 cmminus;1for DNO. Analysis of transitions from vibrationally excited ions gives a ngr;2fundamental frequency of 1153plusmn;170 cmminus;1in HNOminus;and 1113plusmn;170 cmminus;1in DNOminus;. A study of the angular distribution of the photodetached electrons yields the values of bgr;, the anisotropy parameter, for the various transitions in the spectrum. A Franckndash;Condon factor analysis of the HNOXtilde;thinsp;1Aprime; band results in an estimate of the Nndash;O bond length in the negative ion of 1.33plusmn;0.02 Aring;.