Experimental evidence of picosecond to femtosecond molecular motion of the macrocycles 12-crown-4 and 15-crown-5 in cyclohexane at 25 °C

Autor:	Randall B. Shirts, Meizhen Xu, Edward M. Eyring, Sergio Petrucci
Rok vydání:	2000
Předmět:	Permittivity Cyclohexane Terahertz radiation Analytical chemistry General Physics and Astronomy Molecular physics chemistry.chemical_compound symbols.namesake chemistry 15-Crown-5 Picosecond Femtosecond symbols Dielectric loss Debye function Physical and Theoretical Chemistry
Zdroj:	Physical Chemistry Chemical Physics. 2:2297-2300
ISSN:	1463-9084 1463-9076
DOI:	10.1039/b000845l
Popis:	Values of the dielectric loss coefficient, e″, part of the complex permittivity, e*=e′−ie″, from UHF to terahertz (THz) frequencies, are reported for the macrocycles 12-crown-4 (12C4) and 15-crown-5 (15C5), in the solvent cyclohexane at 25°C. The coefficients of the real part of the complex permittivity e′ at UHF-microwave frequencies, and the refractive indices in the visible, at the sodium doublet (λ=589.3 nm), are also reported. The data are described by the sum of three Debye relaxation functions in the microwave region, and by three Rocard–Powles functions in the terahertz, far-IR range of frequencies. The molecular origin of the three Debye functions, following Vij and Hufnagel (J. Phys. Chem., 1991, 95, 6142), is attributed to rotation of the macrocycles along the molecular axes. The source of two Rocard–Powles functions is assigned to molecular librations while one describes a weak solvent absorption.
Databáze:	OpenAIRE
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