掺杂分子晶体NH_（4－x）D_xNO_3相变中的分形行为──NO_3~－u_1、u_4振动模临界态拉曼峰强的研究

掺杂分子晶体ＮＨ＿（４－ｘ）Ｄ＿ｘＮＯ＿３相变中的分形行为──ＮＯ_３~－ｕ＿１、ｕ＿４振动模临界态拉曼峰强的研究马树国，吴国祯（清华大学物理系北京１０００８４）ＴｈｅＦｒａｃｔａｌＩｎｔｅｒｐｒｅｔａｔｉｏｎｏｆｔｈｅＰｈａｓｅＴｒａｓｉｔｉｏｎｏｆ...

The Fractal Interpretation of the Phase Trasition of the Crystalline NH_4-xD_xNO_3 System as Evidenced by The Critical Raman lntenslty Behavior of The Nitrate u_1 and u_4 Modes

Abstract The critical Raman intensities of the nitrate u_l and u_4 modes are shown to behave as |T-T_c|~B .KThis behavoris interpreted from the fractal viewpoint．Deuteriation is shown to affect differently on the u_1 and u_4 mod-esthrough the exponent β．The exponent βis expressed as the product of two factors relating to the energy barrier between the two coexistent phases in the critical region and the degrees of the structural orders of the respective phases.Therefore， accompanied with the thermodynamical measurement of △H，w.are able to obtain paramters concerning the structural orders of the phases in the critical region and the effect by deuteriation. The Raman intensity ratios of the u_1 to u_4 modes also behave as power functions of|T-T_c|， suggesting that the size effect of microdomains of both phases， which fluctuate randomly by the thermal agitation， on the Raman cross sections in the critical region is sig-nificant and in a fractal way.