scispace - formally typeset
Search or ask a question
Journal ArticleDOI

Photoluminescence quenching technique: A sensitive probe for detecting organic vapors at low PPM

01 Aug 2011-International Journal of Nanoscience (World Scientific Publishing Company)-Vol. 10, pp 777-781
TL;DR: In this article, photoluminescence (PL) quenching technique was used to study and analyse sensor parameters like sensitivity, response time and recovery time at low ppm, and the morphological changes in porous structure and the chemical nature of organic adsorbates were the primary reasons for sensing by porous silicon.
Abstract: Crucial sensor parameters like sensitivity, response time and recovery time at low ppm were studied and analysed by photoluminescence (PL) quenching technique A comparison was drawn from various porous silicon samples prepared under different electrochemical anodization conditions Porosity dependent sensing results were analysed and it was observed that samples turned more sensitive with an increase in porosity Samples were tested in the presence of linear aliphatic alcohols (methanol to n-octanol) and water in the range of 10–100 ppm Trifling response was shown for water, while a discernible change in sensitivity was observed when samples were tested with alcohols The morphological changes in porous structure and the chemical nature of organic adsorbates were ascertained to be the primary reasons for sensing by porous silicon
Citations
More filters
Journal ArticleDOI
TL;DR: The present review describes the fabrication of nano-porous silicon and its biosensing capabilities for detection of various analytes including, but not limited to, glucose, DNA, antibodies, bacteria and viruses.

163 citations

Journal Article
TL;DR: In this paper, a relaxation in the q-vector selection rule for the excitation of the Raman active optical phonons was proposed to increase the red shift and broadening of the signal from microcrystalline silicon films.
Abstract: The red shift and the broadening of the Raman signal from microcrystalline silicon films is described in terms of a relaxation in the q-vector selection rule for the excitation of the Raman active optical phonons. The relationship between width and shift calculated from the known dispersion relation in c-Si is in good agreement with available data. An increase in the decay rate of the optical phonons predicted on the basis of the same model is confirmed experimentally.

105 citations

Journal ArticleDOI
TL;DR: This study provides a route for preparing highly sensitive organic vapour sensors with a precise selection of the fabrication parameters and demonstrating their prolonged performance by fabrication using a photoluminescence quenching technique.
Abstract: Surface stability is achieved and demonstrated by porous silicon (PS) fabricated using a wavelength-dependent photo-electrochemical (PEC) anodization technique. During anodization, the photon flux for all wavelengths was kept constant while only the effect of light wavelength on the surface morphology of PS was investigated. PS optical sensors were realized, characterized and tested using a photoluminescence (PL) quenching technique. An aliphatic chain of alcohols (methanol to n-octanol) was detected in the range of 10?200?ppm. Long term surface stability was observed from samples prepared under red (750?620?nm) and green illumination (570?495 nm), where the PL quenching cycles evoke the possibility of using PS for stable sensor device applications. This study provides a route for preparing highly sensitive organic vapour sensors with a precise selection of the fabrication parameters and demonstrating their prolonged performance.

17 citations

Journal ArticleDOI
TL;DR: In this article, a simple and compact design of portable optical sensors, applicable for water vapour sensing is proposed, which is tested as sensors in the presence of linear aliphatic alcohols and water vapours in the wide range of 0-400 ppm.
Abstract: Selective detection of trace level water vapours by functionalized porous silicon (PS) using photoluminescence (PL) quenching technique is reported. This sensitive technique provides sensing data through optical probing on a surface with a submicron surface area. PS samples were prepared via electrochemical etching and were functionalized using ammonium sulphide and UV exposure which brought about major changes in the surface properties. Samples were examined using SEM, FTIR, contact angle and PL spectroscopy. These samples were tested as sensors in the presence of linear aliphatic alcohols and water vapours in the wide range of 0–400 ppm. An increasing trend of sensor response with increase in alcohol chain length and minimal response to water vapours was observed from sensors based on as-anodized PS samples whereas post functionalization, sensors portrayed an opposite response wherein selective response to water vapours and minimal response to alcohols was indicated. The role of surface nitridation is highlighted in selective sensing of water vapours. A correlation between the sensing response and surface chemistry of samples has been established. It is implicated that sensing is directly linked to both the chemical properties of the sensing surface and analytes. A highly sensitive sensor for detection of water vapours at low ppm is presented. A simple and compact design of portable optical sensors, applicable for water vapour sensing is proposed.

8 citations

Journal ArticleDOI
TL;DR: In this article, a single-plane multi-zone nano-porous silicon (n-PS) was prepared using laser-induced electrochemical etching technique and optical sensing studies were performed.

6 citations

References
More filters
Journal ArticleDOI
TL;DR: In this paper, a relaxation in the q-vector selection rule for the excitation of the Raman active optical phonons was proposed to increase the red shift and broadening of the signal from microcrystalline silicon films.

2,059 citations

Journal ArticleDOI
TL;DR: In this article, the effect of the exact shape of the microcrystal and the relationship between the width, shift and asymmetry of the Raman line is calculated and is in good agreement with available experimental data.

1,957 citations

Journal ArticleDOI
TL;DR: The optical properties of porous silicon microcavities are strongly dependent on the environment as discussed by the authors, and both the luminescence intensity and peak position are affected by organic substances, giving the possibility to obtain dual-parameter optical sensors.
Abstract: The optical properties of porous silicon microcavities are strongly dependent on the environment. For highly luminescent samples, both the luminescence intensity and the peak position are affected by organic substances, giving the possibility to obtain dual-parameter optical sensors. While the peak position depends on the organic compound refractive index, luminescence intensity depends on its low-frequency dielectric constant. This allows the discrimination between different organic substances. This sensor is particularly interesting for solvents with low dielectric constant, where the response of electrical sensors is very weak.

227 citations

Journal ArticleDOI
TL;DR: In this article, the photoluminescence observed from porous Si is revesibly quenched on exposure to organic solvent molecules, indicating that this material is extremly surface sensitive.
Abstract: In this work, we report that the photoluminescence observed from porous Si is revesibly quenched on exposure to organic solvent molecules, indicating that the photoluminescence of this material is extremly surface sensitive.

174 citations

Journal ArticleDOI
TL;DR: In this article, a porous silicon multilayer, constituted by a Fabry-Perot cavity between two distributed Bragg reflectors, is exposed to vapor of several organic species and different resonant peak shifts in the reflectivity spectra, ascribed to capillary condensation of the vapor in the silicon pores, are observed.
Abstract: A porous silicon multilayer, constituted by a Fabry–Perot cavity between two distributed Bragg reflectors, is exposed to vapor of several organic species. Different resonant peak shifts in the reflectivity spectra, ascribed to capillary condensation of the vapor in the silicon pores, have been observed. Starting from experimental data, the layer liquid volume fractions condensed in the sensing stack have been numerically estimated. Values ranging between 0.27 (for ethanol) and 0.33 (for iso-propanol) have been found. Time-resolved measurements show that the solvent identification occurs in less then 10 s.

60 citations