50However, heat energy is often transferred more easily from almost any substance to another
because the phonons responsible for vibrational and rotational energy levels in a substance have
much less energy than photons invoked for the electronic energy transfer.
Thus, because vibrational and rotational energy levels are more closely spaced than electronic
energy levels, heat is more easily transferred between substances relative to light or other forms
of electronic energy. For example, ultraviolet electromagnetic radiation is not transferred with as
much efficacy from one substance to another as thermal or electrical energy.
The existence of characteristic energy levels for different chemical substances is useful for their
identification by the analysis of spectral lines. Different kinds of spectra are often used in chemical
spectroscopy, e.g. IR, microwave, NMR, ESR, etc.
Spectroscopy is also used to identify the composition of remote objects - like stars and distant
galaxies - by analyzing their radiation spectra.
The term chemical energy is often used to indicate the potential of a chemical substance to undergo
a transformation through a chemical reaction or to transform other chemical substances.