Infrared absorption spectra and line strengths in the v3 H-O-N bending mode of trans-HONO near 1255 cm-1 have been measured with a tunable diode laser spectrometer. High purity HONO (>98%) was produced by a reaction of gaseous HCl with solid NaNO2. Absolute HONO concentrations were determined either by ion chromatography or by a NOx chemiluminescence analyser.

Line strengths of the strongest lines observed were found to be in the range of (7--12)¿10-21 cm under near Doppler-limited conditions and differ significantly from literature data. In addition, the dependence of the line width on the total air pressure was investigated in the range 0.5--25 Torr, and also the possibility of measuring HONO atmospheric mixing ratios with a tunable diode laser was assessed. ¿ American Geophysical Union 1995.