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Vibrational and rotational dynamics of cyanoferrates in solution
Gerald M Sando1, Q Zhong, J C Owrutsky
1Code 6111, US Naval Research Laboratory, Washington, DC 20375-5342, USA.
The Journal of Chemical Physics
|July 21, 2004
Summary
Ultrafast spectroscopy reveals vibrational energy relaxation (VER) and reorientation (Tr) times for cyanide and nitroso compounds. Shorter VER times were observed for hexacyano species and SNP
Area of Science:
- Physical Chemistry
- Spectroscopy
- Chemical Dynamics
Background:
- Vibrational energy relaxation (VER) and reorientation (Tr) are crucial molecular dynamics processes.
- Understanding these dynamics in transition metal complexes provides insight into their chemical behavior.
Purpose of the Study:
- To measure VER and Tr times for potassium ferrocyanide, ferricyanide, and sodium nitroprusside (SNP) in various solvents.
- To investigate the influence of solute charge, symmetry, and solvent properties on these relaxation dynamics.
Main Methods:
- Ultrafast infrared spectroscopy was employed to probe transient absorptions.
- Anisotropy decay measurements were used to determine reorientation times.
Main Results:
- Short VER times (4-43 ps) were observed for hexacyanoferrates and the NO band of SNP, while the CN band of SNP relaxed more slowly (55-365 ps).
- Reorientation times (Tr) for SNP varied by vibrational band, with longer times for the NO mode (>15 ps) attributed to molecular rotation and shorter times for the CN band (<10 ps) to dipole orientational relaxation.
- Solvent dependence of VER times was similar across solutes, resembling that of triatomic ions.
Conclusions:
- Solute charge and symmetry significantly influence VER.
- Solubility in polar solvents contributes to faster VER.
- No evidence of intramolecular vibrational relaxation (IVR) was found.