Term information
Spectroscopy was originally the study of the interaction between radiation and matter as a function of wavelength. Historically, spectroscopy referred to the use of visible light dispersed according to its wavelength, e.g. by a prism. Later the concept was expanded greatly to comprise any measurement of a quantity as a function of either wavelength or frequency. Thus, it also can refer to a response to an alternating field or varying frequency ( ). A further extension of the scope of the definition added energy (E) as a variable, once the very close relationship E = h for photons was realized (h is the Planck constant). A plot of the response as a function of wavelength or more commonly frequency is referred to as a spectrum; see also spectral linewidth. source: http://en.wikipedia.org/wiki/Spectroscopy
time-resolved spectroscopy
spin-echo method
x-ray spectroscopic technique
Stark spectroscopy
x-ray spectroscopic techniques
Raman spectroscopy
Stark effect spectroscopy