PHYS 4910 Spectroscopy
Assignment 2

  1. For reasons that we discussed in class the effective optical region for this class is between 300 nm and 1000 nm. Within this optical portion the visible section lies between roughly 400 nm and 700 nm. It is also useful to have an idea of the characteristics in terms of frequency and energy

    Wavelength (nm)
    Note: these are all air wavelengths
    Wavelength (Å) Frequency (Hz) Energy (eV) Energy (cm-1)
    257.6 (strong uv line from Hg, used in black lights)
    388 (strong line of helium)
    515.4 (green line for the Ar+ laser
    656.2 (Balmer alpha line of H)
    486.1 (Balmer beta line of H)
    434 (Balmer gamma line of H)
    410.1 (Balmer delta line of H)
  3. The (air) wavelengths of the two D lines of sodium are 589.0 and 589.6 nm. Both terminate on the ground state (E=0). From this information, what are the energies (in cm-1 and in eV) of their respective energy levels
  4. The potassium atom has a pair of D lines, just as sodium does. They also start on the first two excited energy levels and terminate on the ground state. Look up the energies of these two excited levels (see Internet resources), and calculate the D line wavelengths.