Persistent infrared laser induced spectral holes in hydrogen bonded polymers

Persistent spectral holes were burned into the profile of the hydrogen bonded OH stretching absorption, near 3500 cm−1, of three polymeric alcohols. The mechanism is an IR induced conformational change of a H-bonded OH group to weaken the hydrogen bond. In one polymer, an empirical quantum efficiency of about 5×10−3 was measured and a hole depth of 20% of the absorption was achieved with a low power cw laser. The conformational changes occur near the bond which is excited and before extensive intramolecular vibrational randomization.