When taking pictures of scientific instruments at CHANL recently, I was introduced to the "Curmudgeon." His handler told me that this piece of equipment can be quite temperamental, hence the name. Mr. Curmudgeon is actually a x-ray photoelectron spectrometer, XPS. He bombards the surface of your sample with x-rays which have enough energy to remove electrons from the sample surface. These electrons have energies that are characteristic of the elements from which they came. XPS therefore allows probing the chemistry of the sample surface's top ~10 nm.