Profile

Reader in Chemical Spectroscopy

Research area:- Raman and infrared spectroscopy
Fax: 01227 827724
Email: J.A.Creighton@kent.ac.uk

Research Interests

RESEARCH KEYWORDS: Raman and infrared spectroscopy, with particular emphasis on the following areas: (1) Surface-enhanced Raman spectroscopy, both with regard to its applications and to the development of the theory of the phenomenon. (2) zeolite vibrational spectroscopy, including computer modelling of zeolite framework dynamics. (3) chemistry and optical properties of metal colloids. (4) inorganic structural applications of vibrational spectroscopy.

1. Surface-Enhanced Raman Spectroscopy (SERS): SERS is a technique for the investigation of molecules and molecular processes at certain metal surfaces, and it combines ultra-high sensitivity and surface specificity to a remarkable degree. We have been concerned both with the development of a theoretical understanding of the technique and with its applications, particularly in electrochemistry and metal colloid chemistry. Recent work has concentrated on the possibility of designing and fabricating metal particle shapes or surface morphologies which will widen the range of metals to which the SERS technique is applicable, and on the possibility of extending the technique to obtain information about non-metallic surfaces. Analytical applications of SERS, such as its use for environmental monitoring, are also under investigation.

2. Spectroscopy of Zeolites: Spectroscopic techniques have an important role in the study of zeolites because of the difficulties of applying diffraction methods to elucidate the structures these substances. Recently we have developed methods to computer simulate the infrared and Raman spectra of important zeolite framework types. The full interpretation of the experimental spectra automatically follows from this, and has shown that the spectra provide quantitative information on the framework geometries and force constants, and on the ordering of silicon and aluminium atoms in the frameworks. This work is being extended to a wider range of crystalline microporous solids, including gallosilicates and aluminium phosphates.

3. Metal Colloids: We have used Mie theory to calculate the absorption spectra of over 50 of the metallic elements from the optical constants of the bulk metals, and the effects of changing the shapes of the particles has been investigated in a systematic way. This has established which colloidal metals show discrete absorption bands in the visible range, and is important not only for identifying new metals which may be able to exhibit SERS, but also for finding those metals which may have applications as colloidal high-temperature stable colorants, for example for use in ceramics. This work has lead to research into other inorganic materials which may have applications as pigments for use at high-temperatures, especially those containing transition metal oxy-anions.

4. Inorganic Structural Applications: A long term interest has been the applications of infrared and Raman spectroscopy in inorganic chemistry. This work has included the investigation of molecular structures and intermolecular interactions in solution, and the calculation of force constants and statistical thermodynamic data from vibrational spectra. Much of this work has been on metal complexes, and has also involved metal cluster compounds with the aim of investigating the bonding in these metal polyhedra.