Study of the Phase Transition in NaNO_2 Polarized Infrared Radiation

概要

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The absorption spectra of the fundamental v_2 of the nitrite ions in NaNO_2 crystals were investigated over the temperature range between 25℃ and 190℃ with infrared radiation plane-polarized at various angles with respect to the crystallographic axes. Marked changes were observed around the transition point of 163℃. The contours of the absorption band tell us that the amplitude of the torsional oscillation of the nitrite ions around the a axis is fairly large as compared with the amplitude around the c axis. The amplitude around the a axis grows larger with increasing temperature, whereas that around the c axis remains very limited over the whole range of temperatures of experiments. The contours of the absorption band observed with polarized radiation parallel to the θ axis show no trace of inversion doubling even in the high temperature phase. Hence the possibility of the tunneling of the N atoms through the potential hill was ruled out.
社団法人日本物理学会の論文
1961-11-05