DGVCL EXAM PAPER (11-12-2011) QUIZ

None of these

a molecule returns to the electronic ground state from an excited triplet state 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 lowers its vibrational energy by losing it's excess energy as a photon

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

Because fluctuations in the dipole moment allow the molecule to deform by bending and stretching

All 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 its excess energy to light, and emits a photon

A molecule converts excess electronic energy to vibrational energy

None of these

To allow for scattering by the sample

None of these

Because the sample won't fluoresce if the incident radiation is of low power

Because the magnitude of the output signal is proportional to the power of the incident radiation

To prevent thermal degradation of the phosphorescent species

To decease the efficiency of detector

To promote phosphorescence by slowing the rate of radiationless transfer processes

To increase the efficiency of the detector

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)

Wavelength in nanometers x wavenumber = 1

None of these

Wavenumber - wavelength in nanometers = 1

Wavenumber = 1 / wavelength in centimeters

To compensate for power fluctuations in the radiation source

All of these

To compensate for beam attenuation by the monochromator

So a reference solution can be used