Knowledge Bank

FTIR absorption spectrum of the \nu $\mathrm{<mrow\; data-mjx-texclass="ORD">3</mrow>}$ vibrational band of CH$\mathrm{<mrow\; data-mjx-texclass="ORD">3</mrow>}$F in solid $para$-H$\mathrm{<mrow\; data-mjx-texclass="ORD">2</mrow>}$ shows a series of lines at regular intervals, which could be assigned to clusters forming CH$\mathrm{<mrow\; data-mjx-texclass="ORD">3</mrow>}$F-($ortho$-H$\mathrm{<mrow\; data-mjx-texclass="ORD">2</mrow>}$), with n = 0 to 12 nderline{119}, 4731(2003)}. However, such a distinct feature appears only in the \nu $\mathrm{<mrow\; data-mjx-texclass="ORD">3</mrow>}$ mode but is not observed in the other vibrational modes. In order to solve this problem, we applied IR-IR double resonance spectroscopy using 3 $\mu$m OPO laser and 9 $\mu$m QC laser to the vibrational bands of CH$\mathrm{<mrow\; data-mjx-texclass="ORD">3</mrow>}$F in solid $para$-H$\mathrm{<mrow\; data-mjx-texclass="ORD">2</mrow>}$. Because, very recently, high resolution cw-QC laser spectroscopy demonstrated a perfect bleaching effect on a spectral peak in \nu $\mathrm{<mrow\; data-mjx-texclass="ORD">3</mrow>}$ mode, nderline{13}, 11587 (2011)}. By bleaching the n=1 component of the \nu$\mathrm{<mrow\; data-mjx-texclass="ORD">3</mrow>}$ band at 9 $\mu$m, we can see a corresponding depletion in the broad spectral feature of the \nu$\mathrm{<mrow\; data-mjx-texclass="ORD">1</mrow>}$ band at 3 $\mu $m.ThissimultaneousdisappearanceofthespectralpeaksisaproofoftheCH${3}$F-($ortho$-H${2}$)$_{n}$ cluster model, and it suggests that all the vibrational bands should be explained by the same model.