{"title":"A correlation between hydroxyl vibrations under compression and anharmonicity: glaucophane as a test case","authors":"Q. Williams","doi":"10.1007/s00269-023-01254-5","DOIUrl":null,"url":null,"abstract":"<div><p>The infrared hydroxyl bands and first hydroxyl combination bands of glaucophane are characterized under pressure. In this weakly hydrogen-bonded mineral, the anharmonicity parameter, as determined from the difference between combinations and the fundamentals, is nearly constant with pressure to 15 GPa, indicating that the ambient pressure value of hydroxyl-bond anharmonicity closely reflects its value at high pressures. Given this near-constancy, the Grüneisen parameters of the hydroxyl stretching vibrations of a wide range of minerals, as derived from the pressure dependence of their O–H stretching frequencies, are correlated with the anharmonic parameter of each vibration, as determined from the ambient pressure offset of the summed frequencies of the fundamental <i>n</i> = 0 to 1 transitions and the frequency of the hydroxyl combination or overtone band corresponding to the <i>n</i> = 0 to 2 transition. This correlation is motivated by (1) the anharmonic origin of the Grüneisen parameter; and (2) the grossly similar form of the interatomic potential governing weak- and medium-strength hydrogen bonding in many minerals. This possible correlation provides a means through which the likely pressure-induced hydroxyl mode shifts of phases might be estimated from ambient pressure near-infrared measurements and emphasizes the importance of near-infrared combination/overtone band measurements. In this context, the combination/overtone bands of high-pressure hydrous phases are almost completely uncharacterized, and thus one probe of their anharmonicity has been neglected. Such information directly constrains the nature of hydrogen bonding in these phases, and hence provides possible insights into both their retention of hydrogen and its mobility. Deviations from the anharmonicity-Grüneisen parameter correlation, when observed (as may be the case in prehnite), could provide insights into anomalous effects on the hydroxyl potential well induced by bifurcated H-bonds, pressure-dependent Davydov splitting, or the influence of neighboring cations.</p></div>","PeriodicalId":20132,"journal":{"name":"Physics and Chemistry of Minerals","volume":"50 4","pages":""},"PeriodicalIF":1.2000,"publicationDate":"2023-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00269-023-01254-5.pdf","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Physics and Chemistry of Minerals","FirstCategoryId":"89","ListUrlMain":"https://link.springer.com/article/10.1007/s00269-023-01254-5","RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q4","JCRName":"MATERIALS SCIENCE, MULTIDISCIPLINARY","Score":null,"Total":0}
引用次数: 0
Abstract
The infrared hydroxyl bands and first hydroxyl combination bands of glaucophane are characterized under pressure. In this weakly hydrogen-bonded mineral, the anharmonicity parameter, as determined from the difference between combinations and the fundamentals, is nearly constant with pressure to 15 GPa, indicating that the ambient pressure value of hydroxyl-bond anharmonicity closely reflects its value at high pressures. Given this near-constancy, the Grüneisen parameters of the hydroxyl stretching vibrations of a wide range of minerals, as derived from the pressure dependence of their O–H stretching frequencies, are correlated with the anharmonic parameter of each vibration, as determined from the ambient pressure offset of the summed frequencies of the fundamental n = 0 to 1 transitions and the frequency of the hydroxyl combination or overtone band corresponding to the n = 0 to 2 transition. This correlation is motivated by (1) the anharmonic origin of the Grüneisen parameter; and (2) the grossly similar form of the interatomic potential governing weak- and medium-strength hydrogen bonding in many minerals. This possible correlation provides a means through which the likely pressure-induced hydroxyl mode shifts of phases might be estimated from ambient pressure near-infrared measurements and emphasizes the importance of near-infrared combination/overtone band measurements. In this context, the combination/overtone bands of high-pressure hydrous phases are almost completely uncharacterized, and thus one probe of their anharmonicity has been neglected. Such information directly constrains the nature of hydrogen bonding in these phases, and hence provides possible insights into both their retention of hydrogen and its mobility. Deviations from the anharmonicity-Grüneisen parameter correlation, when observed (as may be the case in prehnite), could provide insights into anomalous effects on the hydroxyl potential well induced by bifurcated H-bonds, pressure-dependent Davydov splitting, or the influence of neighboring cations.
期刊介绍:
Physics and Chemistry of Minerals is an international journal devoted to publishing articles and short communications of physical or chemical studies on minerals or solids related to minerals. The aim of the journal is to support competent interdisciplinary work in mineralogy and physics or chemistry. Particular emphasis is placed on applications of modern techniques or new theories and models to interpret atomic structures and physical or chemical properties of minerals. Some subjects of interest are:
-Relationships between atomic structure and crystalline state (structures of various states, crystal energies, crystal growth, thermodynamic studies, phase transformations, solid solution, exsolution phenomena, etc.)
-General solid state spectroscopy (ultraviolet, visible, infrared, Raman, ESCA, luminescence, X-ray, electron paramagnetic resonance, nuclear magnetic resonance, gamma ray resonance, etc.)
-Experimental and theoretical analysis of chemical bonding in minerals (application of crystal field, molecular orbital, band theories, etc.)
-Physical properties (magnetic, mechanical, electric, optical, thermodynamic, etc.)
-Relations between thermal expansion, compressibility, elastic constants, and fundamental properties of atomic structure, particularly as applied to geophysical problems
-Electron microscopy in support of physical and chemical studies
-Computational methods in the study of the structure and properties of minerals
-Mineral surfaces (experimental methods, structure and properties)