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