Leif Fredin

Infrared spectrum of the water dimer in solid nitrogen. I. Assignment and force constant calculations

The infrared spectra of all isotopic water dimers containing H, D, 16O, and 18O have been studied between 4000 cm−1 and 250 cm−1 in solid nitrogen. H‐donating HDO has been observed. The assignment of Tursi and Nixon has been extended to HDO containing dimers. The assignment has been checked by force constant calculations.

On the dimerization of carbon dioxide in nitrogen and argon matrices

Abstract The ir spectrum of carbon dioxide in solid nitrogen and solid argon has been studied. In nitrogen, the NN stretching vibration becomes ir-active in the presence of carbon dioxide. Concentration dependency and diffusion studies allow the identification of a carbon dioxide dimer in solid argon. In solid nitrogen no clear evidence for a dimer was obtained.

Infrared spectrum of the water dimer in solid nitrogen. II. Temperature and irradiation effects

The water dimer in solid nitrogen may exist in a stable and a metastable form. Transitions between the two forms are initiated by infrared radiation absorbed by the dimer fundamentals. The metastable form reverts to the stable form by a dark process. D‐donating DOH may be transformed into H‐donating HOD by infrared radiation. H‐donating HOD is metastable and changes back to D‐donating DOH by a dark (thermal) process.

On the structure of the ethylene chlorine complex

Abstract An ethylene chlorine complex has been prepared in a nitrogen matrix at 20 K. Its ultraviolet and infrared spectra have been recorded. The results are compared with CNDO/2 calculations of structure. Both infrared data and CNDO calculations favor a C 2v symmetric complex. The CNDO calculations predict that the ClCl bond is orthogonal to the ethylene plane. The infrared data give no evidence for or against this prediction. Photolysis of the complex leads to the formation of 1,2-dichloroethane.

On the interaction between ammonia and carbon dioxide in solid argon and solid nitrogen

Abstract Infrared spectra of nitrogen and argon matrices containing ammonia and carbon dioxide have been recorded. A 1:1 ammonia carbon dioxide complex has been observed. The geometry of the complex has been deduced from its infrared spectrum. Carbon dioxide disturbs the rotation of ammonia in argon.

On the rotation of ammonia and the ammonia chlorine complex in solid nitrogen

Abstract Th ν3 and ν4 regions of ammonia and the ammonia chlorine complex in solid nitrogen at temperatures below ca. 15 K show a fine structure which disappears reversibly as the temperature is increased to ca. 20 K. The low temperature spectrum is interpreted in terms of a hindered rotation around the C3 axis of ammonia.

On the structure of the water dimer

Abstract The infrared spectrum of the mixed water dimer H 2 O·D 2 O has been observed at 20 K in a nitrogen matrix. The O-H(D) … O stretching vibrations are found to be slightly shifted compared to the corresponding vibrations in (H 2 O) 2 and (D 2 O) 2 . The results are interpreted as evidence for the open dimer structure of Tursi and Nixon.

Spin conversion in ammonia. A nitrogen matrix isolation study

Abstract The proton spin populations of ammonia in solid nitrogen vary with temperature roughly as expected if ammonia is an axial rotor with a sixfold barrier of ≈140 −1 cm −1 . Precise determinations of the spin popuiations were difficult because of the extreme sharpness of the fine structure components at low temperatures. At temperatures below 15 K the ν 2 , band of ammonia is split into two equally intense components, possibly due to the inversion.

An infrared and CNDO study of a water-chlorine complex

Abstract The infrared spectrum of a water-chlorine complex in a nitrogen matrix at 20 K has been recorded. The results are compared with CNDO/2 calculations of structure and vibration spectra. The isotope shifts of the asymmetric stretching vibration of water is used to calculate the HOH angle in monomeric water and in the water-chlorine complex.