Ok Gentlemen, here is a true science based project for you guy's who know how to program Arduinos (screw PICS!). Here's a website that has the code for this project:
https://wiki.brandoncurtis.com/w/DIY_NMR_Spectroscopy. Just do me the favor and post your results so I can build one for gold prospecting. I recently bought a used Deep UV-Xray Photodiode made by OSI optoelectronics that goes from 200nm to .07nm and was designed to be used for Xray spectroscopy. OSI gives you a single opamp circuit to use with the detector so that will be my project to get into XRF Analysis.
Enjoy