No abstract

Saturable absorbers and optical limiters have contrary optical transmission properties. We report observations of simultaneous occurrence of both these effects in a nickel sulfide nanoparticle (average diameter ~5 nm) solution and a simultaneous quantitative measurement of both. Intensity-dependent nonlinear transmission studies carried out using a 7 ns Nd : YAG laser at 532 nm by the Z-scan method, revealed efficient optical limiting in nickel sulfide nanoparticle suspensions. Induced nonlinear optical scattering was identified to be the mechanism of optical limiting, and absorption at 532 nm was found to saturate. A modification of the conventional Z-scan implementation led to the retrieval of the saturation intensity, which is otherwise overshadowed by very strong nonlinear scattering.

No abstract

No abstract

We report a novel nanocomposite composed of halloysite nanotubes (HNT) and gold nanoparticles (AuNPs) as an excellent sensing platform. Electrodeposition of AuNPs was carried out by cyclic voltammetry for 120 seconds on HNT/GCE in acidic medium to form Au/HNT/GCE. The nanocomposite was characterized by UV-visible spectroscopy and Scanning Electron Microscopy. Higher surface area was created by drop casting HNT which helped in adhering high number of AuNPs that gave rise to enhanced catalytic sites. The modified electrode was used to simultaneously detect dopamine (DA) and serotonin (SE) at nanomolar concentrations. Oxidation peaks of DA and SE was found at 0.3 V and 0.6 V adapting the differential pulse voltammetry. The limit of detection was calculated to be 9.7 × 10-6 M and 92 × 10-9 M for DA and SE respectively with S/N=3. The modified electrode exhibited high sensitivity and stability towards detection of DA and SE.