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The FTIR spectra of pure and isotopically diluted (H/D and D/H) polycrystalline L-glutamine, L-hystidine, L-tyrosine, DL-serine, L-threonine, di-, tri-glycine and di-glycine x HCl x H2O salt were measured in the range 4000-2000 cm(-1) at temperatures from 300 to 10 K. The frequencies of decoupled proton stretching mode bands upsilon1, which can be observed only at low temperature, were used for estimation of the of upsilon1-bands red shift, which occurs upon formation of H-bonds involving ionized NH3+ and/or peptide HN-CO groups. The empirical correlation between the red shift and H-bond length, which was found previously for binary gas phase H-bonded complexes, carbohydrates and nucleosides [M. Rozenberg, A. Loewenschuss and Y. Marcus, Phys. Chem. Chem. Phys., 2000, 2, 2699-2702; M. Rozenberg, C. Jung and G. Shoham, Phys. Chem. Chem. Phys., 2003, 5, 1533-1535], was now extended to H-bonded networks in polycrystalline amino acids and peptides. The energies of the different H-bonds present in the crystalline structures could also be successfully estimated from the well-established empirical correlation [A. V. Iogansen, Spectrochim. Acta, 1999, A55, 1585-1612] between this property and the red shifts of the corresponding upsilon1 mode bands.

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The FT-IR spectra of polycrystalline DL-serine [a-amino-b-hydroxypropionic acid; HO-CH 2 -CH(NH 3 ) + -COO À ] and isotopically substituted [ND/OD Alcohol (<10% and >90% D); CD 2 (>98% D)] DL-serine were recorded in the range 4000-500 cm À1 in the temperature range 300-10 K, and fully assigned. The isotopic-doping/low-temperature methodology, which allows for decoupling of individual proton vibrational modes from the crystal bulk vibrations, was used to estimate the energies of the different H-bonds present in DL-serine crystal. To this end, the frequency shifts observed in both the NH/OH stretching and out-of-plane bending spectral regions (relatively to reference values for these vibrations in nonhydrogen-bonded DL-serine molecules) were used, together with previously developed empirical correlations. The results are compared with available structural data on this amino acid. #

The matrix isolation infrared spectra of "dry" and "wet" vapors of sulfuric acid have been investigated as trapped in solid argon matrices. The availability of a spectrum of trapped anhydrous acid vapor and its comparison with the spectra of trapped water containing vapors of the acid allowed the identification of the hydrogen-bonding shifted hydroxyl bands for both the acid and the water moieties of the monohydrated H(2)SO(4).H(2)O complex. The experimental results are compared to the various theoretically calculated wavenumber values of the acid and its monohydrated complex. The complex stabilization energies, as obtained from calculations and empirical correlations, are compared.