Micro-Raman study on the conformation behavior of succinate in supersaturated sodium succinate aerosols.
Micro-Raman spectra of supersaturated aerosols of sodium succinate were obtained. The conformation behavior of the succinate dianion as a function of relative humidity (RH) was investigated by combining micro-Raman spectroscopy with theoretical calculations. A shoulder at 968 cm(-1) of the v(C-CO(2)(-)) band on the rise in more concentrated droplets was believed indicative of conformation transformations. The intensity ratio (I(963)/I(997)) of the v(C-CO(2)(-)) band at 963 cm(-1) to the v(C-C) band at 997 cm(-1), versus the molar water-to-solute ratio (WSR), was used to fathom the equilibrium between gauche and trans conformations. Before saturation (WSR = 25.8) for the droplets, the ratio of I(963)/I(997) retains a value of approximately 2.6 independent of WSR, indicating that the equilibrium was not disturbed in the dilute droplets. In supersaturated droplets (WSR < 25.8), however, the ratio sharply decreases from approximately 2.6 to approximately 1.1 at WSR = 9.6, which was attributed to the formation of contact ion pairs (CIPs).
Wang
Feng
F
The Institute of Chemical Physics, Beijing Institute of Technology, 100081, Beijing, China.
Zhang
Yun-Hong
YH
Zhao
Li-Jun
LJ
Zhang
Hao
H
Cheng
Hua
H
Shou
Jing-Jing
JJ
D000336:Aerosols; D008968:Molecular Conformation; D012964:Sodium / Q000737:chemistry*; D013059:Spectrum Analysis, Raman; D019802:Succinic Acid / Q000737:chemistry*
D000336:Aerosols; D012964:Sodium; D019802:Succinic Acid