Free software to make energy level diagrams?

[Xgkkp]

Hi, I am currently doing the write up for a project (Mercury spectroscopy), and would like to put some energy level diagrams in, with the transitions being shown.

Does anyone know any software (preferably free/open source) that could do this, or help? Or if there is a way to do it in latex directly that would also be good. Otherwise, does anyone know anywhere I could get a template to use?

 

[nbo10]

The Openoffice drawing program is good for making figures. Mathamatica can also make figures. And you could also do it in Latex.