HR: 16:35h
AN: MR44A-02    [Abstracts]
TI: Correlation between hydroxyl stretching frequency and O-H...O distance from Raman spectroscopy, crystallography and chemical analysis
AU: * Lu, R
EM: renlu@email.arizona.edu
AF: Department of Geosciences, University of Arizona, Tucson, AZ 85721, United States
AU: Yang, H
EM: hyang@u.arizona.edu
AF: Department of Geosciences, University of Arizona, Tucson, AZ 85721, United States
AU: Costtin, G
EM: gcostin@geo.arizona.edu
AF: Department of Geosciences, University of Arizona, Tucson, AZ 85721, United States
AU: Downs, R T
EM: rdowns@u.arizona.edu
AF: Department of Geosciences, University of Arizona, Tucson, AZ 85721, United States
AB: Correlations between hydroxyl stretching frequency and O-H...O distance have been widely used in research of hydroxyl-bearing materials. There have been only two systematic studies to establish such correlations in the past: one by Nakamoto et al (1955) based on a limited number of relatively simple chemicals and the other by Libowitzky (1999) from an extended list of minerals. However, spectroscopic and crystallographic data used to establish these two correlations were mostly from different specimens, which are likely to have different chemical compositions, especially for natural samples. Difference in compositions may results in variation of bonding environments and hydroxyl vibration frequencies, and consequently affects their correlations. The two previous studies also provided very limited data to constrain the correlation for the strong hydrogen bond region where O- H...O distances are less than 2.6 Å. Furthermore, the two reported correlations were based on infrared and published crystallographic data at the time. No correlation has ever been established from Raman spectroscopy, which has become a powerful and widely available technique for identification and characterization of various materials. The current study provides the first correlation constructed using the hydroxyl stretching frequency data measured from Raman spectroscopy. A highly selected set of over 40 minerals from the large collection of natural samples of the RRUFF project (http:rruff.info) are used for this study. These selected minerals all have simple and well- established hydrogen positions, and cover the region from the very weak to very strong hydrogen bonding. All specimens are fully characterized for their Raman spectroscopy, chemistry, as well as crystal structure particularly for hydrogen positions if existing structural data do not provide sufficient constraint on hydroxyl species for the specific chemical composition, or such data do not exist. Special efforts are given in this study to constrain the correlation in the region where hydrogen bonding characteristics changes from week to strong (O- H...O distance ~ 2.7 Å) and in the region where hydrogen bonding is very strong (O-H...O distance < 2.6 Å). References Nakamoto K, Margoshes M, Rundle RE (1955) Stretching Frequencies as a Function of Distances in Hydrogen Bonds, J Am Chem Soc 77, 6480
Libowitzky E (1999) Correlation of O-H Stretching Frequencies and O-H...O Hydrogen Bond Lengths in Minerals, Monatshefte für Chemie 130, 1047-1059.
DE: 1042 Mineral and crystal chemistry (3620)
DE: 3600 MINERALOGY AND PETROLOGY
DE: 3900 MINERAL PHYSICS
DE: 3934 Optical, infrared, and Raman spectroscopy
DE: 3954 X-ray, neutron, and electron spectroscopy and diffraction
SC: Mineral and Rock Physics [MR]
MN: 2007 Joint Assembly