I would usually do this verbally but this is for someone at work. I have this fear of getting laughed at by the other coworkers if my invitation isn't accepted. I'd rather keep it quiet to mitigate drama.
Most Helpful Guy
So... you'd leave a paper trail? No, don't do that. You don't want it photocopied and dispersed in case she goes all high school on your ass, and on top of that, if she decides you're sexually harassing her, she's got some strong evidence against you. Wait for a discrete time and ask verbally.
Do you really want to ask people out at work? :/0