Infrared spectroscopy is an inherently “faster” method than NMR, and an IR spectrum is a superposition of the spectra of the various conformations, rather than an average of them. When 1, 2-dichloroethane is cooled below its freezing point, the crystalline material gives an IR spectrum consistent with a single species that has a center of symmetry. At room temperature, the IR spectrum of liquid 1, 2-dichloroethane retains the peaks present in the solid, but includes new peaks as well. Explain these observations.