Mercury vapour is used in as the dominant species which is excited in a traditional fluorescent light. The first and second excited states of Mercury occur at 254 and 185 nm.

Question

1. In what region of the electromagnetic spectrum do these transitions occur?
2. Given that these transitions occur mostly outside the visible range, how are these transitions utilised to generate typical room lighting?

Thanks any help will be appreciated.

Answer 1

254 nm is in the UV region of the spectrum; 185 is in the vacuum ultraviolet region.
These wavelengths shine on a fluorescent material that coats the inside of the bulb. The coated is bathed in the UV light, it is absorbed and re-radiated as visible radiation. Here is a site that gives much more information than you are looking for; however, if you will scroll through it, it contains BOTH an explanation of how the fluorescent bulbs work as well as a table of regions where the different
wavelengths fall.
http://en.wikipedia.org/wiki/Ultraviolet