Open Access. The author accepted manuscript version of this work has been reproduced here according to the publishers policies.
This article may be downloaded for personal use only. Permission to reproduce this article must be sought from Elsevier. This is an author's accepted manuscript version of an article published in Vibrational Spectroscopy, 57(2): 306-314, 2011. More information about this journal may be available at http://www.sciencedirect.com/science/article/pii/S0924203111001305