The apparatus for photochemical experiments on solid samples is described elsewhere. The absorption was measured at spectral resolution 0.1 nm the accuracy of reported spectral positions is ☐.04 nm.

The light transmitted through the LiF substrate was incident on a glass window coated with sodium salicylate the converted visible light was detected with a photomultiplier tube (Hamamatsu R943-02) in a photon-counting mode. The far-ultraviolet light was dispersed with a high-flux cylindrical-grating monochromator (focal length 6 m) at beam line BL03 with maximum photon rate about ∼10 12 photons s -1 and maximum resolving power about ∼50,000 a LiF or CaF 2 disc served to remove the light of higher orders. To record the absorption of a condensed sample of NH 3 dispersed in Ne in the far-ultraviolet region, we deposited a gaseous mixture on a cold LiF window attached to a rotatable refrigerator system (Janis RDK-415 or APD HC-DE204S) coupled to beam line BL03. The apparatus for this absorption measurement is described elsewhere. We recorded the far-ultraviolet absorption spectrum of condensed samples and irradiated these samples with light from the synchrotron in Taiwan Light Source at National Synchrotron Radiation Research Center (NSRRC). These advanced techniques have enabled us to detect both nitrogen atoms and dinitrogen molecules as a significant presence in this photolysis system. In this work, the emission spectra were recorded both during irradiation and whilst the sample in darkness warmed from ∼5 K to ∼8 K. In preceding work, we irradiated ammonia dispersed in solid neon with far-ultraviolet light and identified photolysis products NH and NH 2 radicals the features of their electronic and vibrational absorption spectra were recorded in the near-ultraviolet, visible and infrared region. Using intense and tunable radiation from a synchrotron, we have applied our advanced apparatus to record not only absorption spectra of samples near 4 K throughout the near-ultraviolet, visible and near-infrared regions up to 1100 nm but also emission spectra in the same range, and absorption spectra in the mid-infrared region, from 500 to 4000 cm -1. in solidified noble gases have been reported chemiluminescent spectra of N, O 2, NO, N 2 and NH have also been observed during the warming of mixtures of NH 3 and H 2O in solid argon subjected to photolysis with vacuum-ultraviolet light in a broad band. and of emission and excitation of photoluminescence of NH and ND 9,10 9. Visible absorption spectra of NH 2, NHD and ND 2 in Ar, 8 8. Irradiation from 149 to 164 nm of NH 3 in Ar at 4 K generated NH 2 and NH in approximately equal proportions, although prolonged photolysis decreased the yield of NH 2, likely due to secondary photolysis. to both NH 2 and NH after photolysis of NH 3 in solid N 2 a similar experiment involving photolysis of HN 3 in solid Ar generated lines attributed to NH and ND.

Mid-infrared spectral lines were assigned 6 6. in contrast with 160 nm from gaseous NH 3. The photolysis of NH 3 in solid Ar with radiation of wave length less than 200 nm sufficed to generate spectra in the visible and near-ultraviolet region of NH 2 but a wave length less than 155 nm was required to produce NH, 4 4. Following the flash photolysis of gaseous NH 3 and ND 3, an analysis of the complicated electronic absorption spectra of NH 2 and ND 2 incorporated both vibrational and rotational aspects.

Triatomic NH 2 but not NH was identified as a primary photochemical product of the photolysis of also N 2H 4. Gaseous product NH 2 but not NH was identified with its electronic absorption spectra after flash photolysis of NH 3. The products of decomposition of ammonia with ultraviolet light have been investigated extensively for both gaseous ammonia and ammonia in solid dispersions.

Emission spectra