Study of disorder in different phases of tetratriacontane and binary alkane mixture, using vibrational spectroscopy

Abstract

Raman spectroscopy has been used to investigate the monoclinic crystal f rotator f melt phase transitions in n-C34H70, for both real-time heating and cooling runs. Changes in band intensity and frequency in the CH2 bending, CH2 twisting, skeletal C-C stretching, and CH3 rocking regions revealed both transitions, particularly when using band components related to gauche bonds. In the room temperature infrared spectrum, the CH2 rocking-twisting and CH2 wagging progressions were observed and indexed for n-C34H70 and a 2:1 (w/w) mixture of C34H70 and C36D74. This led to best estimates for the all-trans crystal core in both cases of 33 to 34 carbon atoms, indicating that the core corresponds to almost the whole of the C34H70 molecule.