Objective
The spectrum of water vapour is of fundamental importance for a variety of processes including the absorption and retention of sunlight in Earth atmosphere. Therefore, there has long been an urgent need for a robust and accurate predictive model for this spectrum. The absorption and emission of light by water vapour is responsible for about 70 % of the known absorption of sunlight and the majority of the greenhouse effect. Hot steam is also a major product of most combustion processes and a dominant atmospheric constituent of cool stars. Water spectra have therefore been the subject of immense scientific effort but some properties, such as the details of atmospherically important weak line absorptions or the spectrum of superheated water, are extremely difficult to determine experimentally. Similarly, despite significant progress in this area, there exists no complete and accurate theoretical model with which one can predict the high-resolution spectrum of water.
The present programme will aim to construct a complete line list for the water problem. The line list will include theoretical and (where available) experimental values of transition frequencies, intensities, pressure effects parameters for all major water isotopomers. To solve the problem both high quality experiments to characterize the spectra of water (and its isotopomers) at a number of wavelengths, temperatures and new theoretical methods of calculating spectra, based on both variational and perturbative treatments of the problem, will be developed and applied. In the experimental part of the proposal a number of ultra sensitive absorption laser techniques including Intracavity Laser Absorption Spectroscopy, Cavity-Ring Down Spectroscopy, Cavity Enhanced Absorption Spectroscopy will be used. Two complementary approaches variational and perturbative treatments of the rotation-vibration problem will be employed and new methods within these approaches will be developed. Effective Hamiltonians methods give better accuracy but for limited spectral regions while variational calculations can provide overall outline of whole water spectrum.
This proposal combines the efforts of laboratories, which have made major contributions to the theoretical and experimental studies of water spectra. They will deliver a comprehensive solution to the water spectral problem, which has many important uses. Application of the methods developed to related triatomic molecules such as H2S will also be explored. The participating teams have immense experience developing spectroscopic experimental and theoretical methods and applying them for measuring and analysing molecular spectra.
New experimental and theoretical data would be included in the present spectroscopic databases (HITRAN, GEISA...) and distributed via the World Wide Web. The results of the project will be of great interest for scientists studying Earth atmosphere, combustion processes, and atmospheres of cool oxygen rich stars.
Topic(s)
Call for proposal
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WC1E 6BT London
United Kingdom