I refer to the article "Cornell College Students Achieve the Highly Improbable" by A. Ault, (J. Chem. Educ. 2000, 77, 1386-1387). The authors give a wrong interpretation for the interesting phototropic reaction. They have failed to study the relevant literature, which should also be given as references; for example:

Sixl, H.; Warta, R. Chem. Phys. 1985, 94, 147-155.
Lehn, J.-M., et al. J. Phys. Chem. 1996, 100, 16175-16186.

According to this, a hydrogen atom is transferred to the nitrogen atom of the pyridine ring and not to an oxygen atom of a nitro group.