Question

A scientist uses the 454.6 nm output from an Ar+ laser to study the vibrational energy levels of pyrimidine. A large peak due to the ring breathing vibration of the molecule is observed in the Stokes Raman spectrum at 990 cm−1. What is the wavelength in nm of the photons corresponding to this peak that the scientist is detecting?

Answer 1

diahon. The Raman spectroscopi kechnique is useful for understanding vibra in molecule. The molecule is rradiated with specific radia The detector can record the same radiation (Rayleigh seat of radiation with decreased energy ( stoves line) or rac increased energy Canti-stonces line). The energy diagram ? (Stokes line) or radiation with nergy diagram loons line following, Virtual energy. states radiation giren for our 7-4546 case, it is shift energy state Rayleigh Stokes Anti Stokes Vibrational 7 stores Stokes scattering I F - 990 cm from Stones Raman / scattering fines lines . spectrum We have to find the warelength of the radiation observed (? Sign in diagram). We can find the energy of emitted radiation by substracting the slowes shift energy (990 cm ) from the incident absorbed radiation energy (corresponding to 454.6 nm). So Eemision = Falsorbed - Estances he asored - he Istories te wavelength he - he x 900 cm (36 x 10 347.5 X 3x10°ms" 6.636810*93.5X30!04 45966 x 10m xgoocan 41.8192 x 10-20 J D= warenumber - hexgony 959.6mm

t emission = be X emission ^ emission = be - 6.636x10 39 J.S X 3x10°ms E mession 41.8192 X10-20 = 0.47604 x 10 m 2 47604 x 1o'm = 476.04 nm -976.04 nm is the worelength of the photons corresponding to the pears that scientist is detecting