Assuming no interaction between vibrational and rotational energy levels in HF, the frequency (in $\mathrm{cm^{-1}}$, rounded off to the nearest integer) of the R branch line originating from J = 4 in its IR spectrum is ________ (Given: Rotational constant for HF = 19.35 $\mathrm{cm^{-1}}$; $\bar{\nu}_0 = 4138.52\ \mathrm{cm^{-1}}$)
Answer
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