Can isotopic ratios be detected via spectroscopy?
I would have bet that all isotopes of the same element would have the same spectroscopic signatures, but then I found this page which had the following:
Spectroscopic techniques are extremely sensitive. Single atoms and even different isotopes of the same atom can be detected among 10^20 or more atoms of a different species. (Isotopes are all atoms of an element that have unequal mass but the same atomic number. Isotopes of the same element are virtually identical chemically.)
Well, what do you know?