An extended phase transition in crystalline L-cysteine near 70 K.
An anomaly of heat capacity near 70 K was registered in the crystalline L-cysteine (orthorhombic polymorph) by adiabatic calorimetry as a small, 3-5% height, diffuse "jump", or a wide "hump" accompanied by the substantial increase in the thermal relaxation time. The Cp(T) dependence is characteristic for a transformation extended over a wide temperature range and sensitive to the thermal prehistory of the sample, that can be interpreted as nonsimultaneous changes in the dynamics and the orientation of the numerous thiol groups in the structure. The measurements of the cell parameters and cell volume on cooling suggest that a discontinuity in their values over the transition point exists.
Paukov
Igor E
IE
Institute of Inorganic Chemistry SB RAS, Lavrent'eva 3, Novosibirsk, 630090, Russia. paukov@che.nsk.su
Kovalevskaya
Yulia A
YA
Drebushchak
Valeri A
VA
Drebushchak
Tatiana N
TN
Boldyreva
Elena V
EV
D003545:Cysteine / Q000737:chemistry*; D044367:Phase Transition; D013696:Temperature
D003545:Cysteine