Molecular photodesorption from single-walled carbon nanotubes

Abstract

Probing the photoelectrical properties of single-walled carbon nanotubes ͑SWNTs͒ led to the discovery of photoinduced molecular desorption phenomena in nanotube molecular wires. These phenomena were found to be generic to various molecule-nanotube systems. Photodesorption strongly depends on the wavelength of light, the details of which lead to a fundamental understanding of how light stimulates molecular desorption from nanotubes. The results have important implications to nanotube-based molecular electronics, miniature chemical sensors, and optoelectronic devices.

Reversible, Band-Gap-Selective Protonation of Single-Walled Carbon Nanotubes in Solution

“…The generally increasing trend with decreasing diameter is consistent with the premise of greater charge transfer from smaller band gap nanotubes strengthening this interaction and decreasing desorption probability. Chen and co-workers 17 estimate a cross section of 1.4 × 10 -17 cm 2 /photon for a large diameter nanotube (E gap ∼ 0.6 eV) from conductance increases following O 2 desorption, and this value is commensurate with those reported in this work.…”

“…The effect of oxygen on nanotube electronic structure and reactivity is not fully understood. Chen et al 17 demonstrate systematic conductance changes as their substrate mounted and semiconducting nanotube was exposed to O 2 and cleaned with UV irradiation. These authors claim that the O 2 withdraws electron density from the nanotube, creating a doped, p-type semiconductor of greater conductance.…”

The optoelectronic properties of a photosystem I–carbon nanotube hybrid system

“…First, all of our samples are measured in vacuum (p < 1 x 10 -3 mbar). Hereby, we can rule out photodesorption effects, where the laser excitation would induce oxygen desorption of the dopant oxygen from the side-walls of the CNTs [10]. To rule out the effect of a Schottky barrier between the CNTs and the gold contacts as the dominating optoelectronic effect, we measure the photoconductance of ensembles of PSI-CNT hybrids, while we spatially scan the excitation spot in the directions x and y with respect to the source-drain contacts (figure 2(a) and (b)).…”

Carbon nanotube‐sensor‐integrated microfluidic platform for real‐time chemical concentration detection

“…In 2001, Chen et al showed that SWNTs appear hole doped in air as a result of donating electrons to oxygen molecules. The responses to different kinds of gas molecules are different due to the difference of binding energy and charge transfer from the molecule to the CNT [17]. These CNT-based chemical sensors can operate at room temperature and give responses to some gases with both high sensitivity of several parts per billion [18] and fast response time of several seconds [19].…”