UV Luminance Spectroscopy Why phosphorescence measurements are usually made at a low temperature? To decease the efficiency of detector To increase the efficiency of the detector To prevent thermal degradation of the phosphorescent species To promote phosphorescence by slowing the rate of radiationless transfer processes To decease the efficiency of detector To increase the efficiency of the detector To prevent thermal degradation of the phosphorescent species To promote phosphorescence by slowing the rate of radiationless transfer processes ANSWER DOWNLOAD EXAMIANS APP
UV Luminance Spectroscopy Why must the radiation source for fluorescence spectrometry be more powerful than for absorption spectroscopy? None of these Because the sample won't fluoresce if the incident radiation is of low power To allow for scattering by the sample Because the magnitude of the output signal is proportional to the power of the incident radiation None of these Because the sample won't fluoresce if the incident radiation is of low power To allow for scattering by the sample Because the magnitude of the output signal is proportional to the power of the incident radiation ANSWER DOWNLOAD EXAMIANS APP
UV Luminance Spectroscopy Internal conversion is where 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 A molecule converts its excess energy to light, and emits a photon None of these 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 A molecule converts its excess energy to light, and emits a photon None of these ANSWER DOWNLOAD EXAMIANS APP
UV Luminance Spectroscopy For a molecule to absorb IR, why must the molecule's vibrations cause fluctuations in the dipole moment of the molecule? All of these Because fluctuations in the dipole moment allow the molecule to deform by bending and stretching Because for absorption to occur, the radiation must interact with the electric field caused by changing dipole moment Because a change in dipole moment lowers the energy required for electronic transitions All of these Because fluctuations in the dipole moment allow the molecule to deform by bending and stretching Because for absorption to occur, the radiation must interact with the electric field caused by changing dipole moment Because a change in dipole moment lowers the energy required for electronic transitions ANSWER DOWNLOAD EXAMIANS APP
UV Luminance Spectroscopy 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 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 ANSWER DOWNLOAD EXAMIANS APP
UV Luminance Spectroscopy In the intersystem crossing a molecule converts its excess energy to light, and emits a photon All 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 All 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) ANSWER DOWNLOAD EXAMIANS APP
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