What is the relationship between wavelength and wave number? Wavenumber - wavelength in nanometers = 1 Wavelength in nanometers x wavenumber = 1 Wavenumber = 1 / wavelength in centimeters None of these TRUE ANSWER : ? YOUR ANSWER : ?
In the intersystem crossing All of these a molecule converts excess electronic energy to vibrational energy a molecule converts its excess energy to light, and emits a photon the spin of an excited electron reverses, changing the state of the molecule (from singlet state to triplet state or vice versa) TRUE ANSWER : ? YOUR ANSWER : ?
Internal conversion is where A molecule converts its excess energy to light, and emits a photon None of these A molecule converts excess electronic energy to vibrational energy the spin of an excited electron reverses, changing the state of the molecule (from singlet state to triplet state or vice versa) TRUE ANSWER : ? YOUR ANSWER : ?
For a molecule to absorb IR, why must the molecule's vibrations cause fluctuations in the dipole moment of the molecule? Because fluctuations in the dipole moment allow the molecule to deform by bending and stretching Because a change in dipole moment lowers the energy required for electronic transitions All of these Because for absorption to occur, the radiation must interact with the electric field caused by changing dipole moment TRUE ANSWER : ? YOUR ANSWER : ?
Why must the radiation source for fluorescence spectrometry be more powerful than for absorption spectroscopy? Because the magnitude of the output signal is proportional to the power of the incident radiation To allow for scattering by the sample None of these Because the sample won't fluoresce if the incident radiation is of low power TRUE ANSWER : ? YOUR ANSWER : ?
Fluorescence occurs when a molecule returns to the electronic ground state from an excited triplet state by losing it's excess energy as a photon a molecule lowers its vibrational energy by losing it's excess energy as a photon None of these a molecule returns to the electronic ground state from an excited singlet state by losing it's excess energy as a photon TRUE ANSWER : ? YOUR ANSWER : ?
Why phosphorescence measurements are usually made at a low temperature? To promote phosphorescence by slowing the rate of radiationless transfer processes To increase the efficiency of the detector To prevent thermal degradation of the phosphorescent species To decease the efficiency of detector TRUE ANSWER : ? YOUR ANSWER : ?
Why do fluorescence spectrometers often use double-beam optics? To compensate for power fluctuations in the radiation source To compensate for beam attenuation by the monochromator So a reference solution can be used All of these TRUE ANSWER : ? YOUR ANSWER : ?