Reversible modification of the absorption properties of single-walled carbon nanotube thin films via nitric acid exposure

Exposure of thin films of as-prepared single-walled carbon nanotubes (SWNT) to nitric acid induces dramatic bleaching of the first and second interband transitions of semiconducting tubes (S1 and S2). These near-IR absorption features can be restored by annealing of treated SWNT films to elevated temperatures. Annealing may also be accomplished by visible laser irradiation thus allowing for spatially resolved modi cations to SWNT thin film optical absorption.