An Emission System of the Io Molecule

Abstract

The "methyl iodide flanle bands", lying in the region 4100 to 6300 a, have been photographed using a 21-ft concave grating spectrograph. The bands are shown to arise from an A211 + X211 transition of the I 0 molecule. Rotational and vibrational analysis of the bands has been carried out and the molecular constants of I 0 obtained. ISTRODUCTION A number of red-degraded bands, now ICIIOWII as the "methyl iodide flame bands", was first observed bl. Vaidya (1937) in emission from a flame of methyl iodide mixed with ~nethyl alcohol or coal gas. The bands were a~~a l y z e d into two systems, A and B, and were tentatively assignecl to the I 0 or CI molecule. Coleman, Gaydon, and Vaidya (1948) obtained the bands in e~nission from all oxyhydrogen flame to which iodine was added, thus supporting the assignment to 1 0 . These authors observed approximately 40 bands in the region 4100 to 6300 A and showed that all the bands could be arranged into one system instead of t~v o . Vibrational constants were given but no rotational analysis was attempted since the b a l d s were observed only ~vith low resolution.Durie ancl Ramsay (1958) observed six bands of the same system in absorption cluring the flash photolysis of mixtures of iodine vapor and oxygen. The bands were observed with high resolution but no rotational analysis of the absorption bands was attempted since the same bancls, extencling to much higher J values, were also observed in emission from an oxyhyclrogen fla~ne to which methyl iodide was added. AlIost of the bands reported by Coleman, Gaydon, ancl Vaiclya were rephotographed under high resolution by Durie and Iiamsay. The rotational and vibrational analysis of these bands forms the main subject of the present paper and confirms the assignment of the bands to the I 0 molecule.The source ~~s e d to excite the methyl iodide flame bands consisted of a diffusion flame of hydrogen, saturated with methyl iodide vapor a t room temperature, burning in an atmosphere of oxygen. The bands were photographed using the second order of a 21-ft concave grating spectrograph ancl Eastman I<odali 103a0, 103aD, 103aB, and 103aF plates. The exposure t i~n e s varied from 1 to 5 hours. An iron arc was used to provide a reference spectrum.

The atmospheric column abundance of IO: Implications for stratospheric ozone

“…I0 was first observed spectroscopically in emission by Vaidya [1938] from a methyl iodide flame source. Durie et al [1960] used a high-resolution grating spectrograph to assign six vibrational bands of the A •-X transition of IO. They noted that the rotational features within the 2-0 vibrational band (445 nm), unlike the other bands, were not broadened beyond the resolution of the spectrograph.…”

Photo-oxidation of Iodomethane in Solid Argon

“…The lines near 3400 and 2500 cm-' are obviously 0-H and 0-D stretching modes. The lines between 540 and 575 cm-' are suitable for 0-1 valence-stretching modes; these values are similar both to the mean, 504 cm-', of wavenumbers of symmetric and antisymmetric stretching modes of 10,-containing molecules (17), and to the single fundamental of the I 0 free radical, 673 and 504 cm-', in its two characterized electronic states (18). The lines near 1190 and 870 cm-' are appropriate to a deformation mode in which most of the amplitude (and kinetic energy) of vibration belongs to the H and D atoms.…”

NIST–JANAF Thermochemical Tables for the Iodine Oxides

“…[62GURIKHA] relied on the results of Vaidya (1937), Blake and Iredale (1946), Coleman, Gaydon, and Vaidya (1948), Durie and Ramsay (1958), and Durie, Legay, and Ramsay (1960). The recommended spectroscopic information given by Huber and Herzberg [79HUBIHER] was based on the data of Coleman et ai.…”

“…The recommended spectroscopic information given by Huber and Herzberg [79HUBIHER] was based on the data of Coleman et ai. (1948), Durie and Ramsay (1958), and Durie et al (1960). The thermochemical table of Brewer and Rosenblatt [69BREIROS] is based on the earlier vibrational and rotational constants data of Durie et al (1960) and the energy level values of Durie et al (1960), Moore (1958), and Herzberg (1950).…”