Laboratory observation of the 2nu2 band of the H3(+) molecular ion

Wavenumbers and assignments are reported for lines of the 2nu2 vibrational band of the H3(+) molecular ion, observed in the range 4500-5100/cm as pressure-enhanced emission lines from a hollow-cathode electrical discharge through molecular hydrogen. The assignments are based on ab initio calculations, previously tested for the nu2 fundamental and for difference bands, and here extended up to angular momentum states with J = 12. Calculated Einstein A(if) coefficients of the lines are presented and imply a rotational temperature of about 1800 + or - 200 K in the laboratory spectrum, which is probably due to emission by excited H{sub 3}(+) formed in the exothermic reaction H{sub 2}(+) + H{sub 2}-H{sub 3}(+) + H. The H{sub 3}(+) 2nu2 band has recently been identified in emission from the auroral hot spots of Jupiter, and the present more extensive data will assist in further astronomical searches for this ion. 33 refs.