Hello lifebookn,
Good question.
In order to generate OH radicals, you need to have some chemical that contains an OH group.
An example of chlorine that is subject to ultraviolet rays and produces two chloride radicals is near the top of the page of the following article:
http://en.wikipedia.org/wiki/Radical_(chemistry)If you were to have an alcohol or other compounds with OH groups, then you would be able to generate OH radicals. Some chemicals form OH radicals easier than others, so it will depend on the type and reaction rate that you are trying to generate.
I hope this helps answer your question.
Best wishes,
Eugene