The question: Given that w=h-bar(L+1)/I. Suppose that we observe spectral lines from the HCl molecule at wave numbers (in cm^-1) 85.03, 103.73, 124.30, 145.03, 165,51 and 185.86 (wavenumber here is simply in the inverse wavelength lambda^-1). What L values do these lines correspond to? My attempt: Knowing that w=2*pi*c/lambda I tried to set up a ratio between to wavenumbers and relate it to the original equation but couldn't find a set of integrals for L that matched my ratios. I don't know what to do. Please help!