mercury discharge produce UV?

In a discharge tube, mercury vapours are bombarded by electrons. The kinetic energy of these electrons is transferred to the mercury atoms, causing excitation of the atoms with orbital electrons jump to higher energy levels. When the excited atoms are de-excited, electrons fall back to their original energy level, emitting photons.

The energy level of mercury atoms is shown on the diagram given in the web-page below:

http://castlelearning.com/review/reference/phys5.htm

As can be seen that the energy level between the ground state and first excited state is 4.64 eV . The wavelength 入 of the emitted photon is given by,

入 = hc/E
where E is the energy of the photon (= 4.64 eV, or 7.42 x 10^-19 J)
h is Planck's constant (= 6.6 x 10^-34 J-s)
c is the speed of light (= 3 x10^8 m/s)

Hence, 入 = 267 nm
Such wavelength falls on the ultraviolet range.