THE NU(5) BAND OF HCLO4

The high-resolution infrared spectrum of perchloric acid has been obse rved in the 700-750 cm(-1) region using the infrared beamline at the M AX-I electron storage ring in Lund, Sweden. The spectrum displays exte nsive rotational structure due to a type a band and is assigned to v(5 ), the HO-ClO3 stretch. Approximately 1100 transitions in (HClO4)-Cl-3 5 and ca. 300 in (HClO4)-Cl-37 have been fitted using single subband a nalysis, generating constants for transitions having the same K. The o rigin of (HClO4)-Cl-35 K = 3t series is found to be 726.9971(4) cm(-1) . Rotationally resolved infrared line positions are now available for the identification of HClO4 in the atmosphere, which may be produced b y the heterogeneous oxidation of chlorine containing species in the st ratosphere. (C) 1998 Academic Press.