  We describe a new optical diagnostic for determining the composition of gases
by measuring the motion of atoms and molecules trapped within very deep optical
lattices. This non-resonant method is analogous to conventional Raman
scattering, except that the observed spectral features relate to the
oscillatory center-of-mass motion of each species within the lattice,
determined uniquely by their respective polarizability-to-mass ratio. Depending
on the density of the probed sample, detection occurs either via optical
scattering at the high end or via non-resonant ionization at the lower end. We
show that such a technique is complementary to conventional mass spectrometry
techniques and envision its implementation in existing instruments.
