An approximate way to subtract the mechanical spectra of deposited materials from a composite reed-vibration method

A new experimental method has been designed to measure the mechanical spectra (complex Young's modulus Y * =Y'+iY'' versus temperature) of materials from liquid to solid state [X.N. Ying, Y.H. Yuan, L. Zhang, Y.N. Huang, Y.N. Wang, X.L. Wang, D.S. Zhou, G. Xue, Rev. Sci. Instr. 77 (2006) 053902]. The mechanical spectrum of material can be obtained by the subtraction from a composite system consisting a substrate reed and materials deposited on the substrate. In this report, an approximate way is shown to subtract the mechanical spectra of the deposited material from the composite system. And normalized mechanical spectra of glycerol and 1,2-propanediol carbonate were reproduced and they fit the data in Ying et al. very well. Furthermore, the approximate way might be more applicable since no regular shape of deposited materials is required