کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
9521532 | 1347781 | 2005 | 13 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
VIS-NIR overtone bands of snow: Photoacoustic spectroscopy
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موضوعات مرتبط
مهندسی و علوم پایه
علوم زمین و سیارات
علوم زمین و سیاره ای (عمومی)
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چکیده انگلیسی
Photoacoustic (PA) spectrum of natural dry snow was obtained in the wavelength range of 200-1100 nm, using an indigenously developed PA Spectrometer (Kapil, J.C., Joshi, S.K., Rai. A.K., 2003. Insitu Photoacoustic Investigations of some optically transparent samples like ice and snow. Review of Scientific Instruments 74 (7), 3536-3543), working in a temperature range of room temperature to â 40 °C. Fundamental frequencies (v1, v2, v3) as well as overtone frequencies of O-H vibrations in a snow crystal were identified and the corresponding combinational frequencies were assigned in the UV-VIS-NIR region of electromagnetic spectrum. The PA spectrum of snow thus obtained was compared with the PA spectra of distilled water and hexagonal ice (ice-Ih), in the same wavelength region. Bathochromic shifts (942â974â983 nm) in the third overtone frequency (3v1) of fundamental O-H vibrations in the H2O molecule were observed when the phase changes as vaporâliquidâsolid. These shifts have been explained in the context of increased contents of hydrogen bonding (skeleton of H-bonds) in the denser phases (liquid and solid) as compared to the rare phase (vapor). The effect of temperature on the creation or breakage of H-bonds in snow crystals has been demonstrated by the relative shifting of the absorption maxima. For monitoring the effect of H-bonding leading to the intricacy in the crystallography of snow, vibrational absorption bands were analyzed from the relative shifting associated to the absorption maxima of snow and snow-melt water at two different wavelengths (535 and 826 nm) near the phase transitions. Also, our investigation reveals that ÎEj (change in vibrational energy) are symmetrically aligned about the Îv-axes (change in vibrational quantum number) at phase transitions.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Cold Regions Science and Technology - Volume 43, Issue 3, December 2005, Pages 164-176
Journal: Cold Regions Science and Technology - Volume 43, Issue 3, December 2005, Pages 164-176
نویسندگان
J.C. Kapil, P.K. Satyawali, D.N. Sethi,