It is a process in which energy absorbed by a substance is released relatively slowly in the form of light. This is in some cases the mechanism used for “glow-in-the-dark” materials which are “charged” by exposure to light. In phosphorescence, the electron which absorb the photon (energy) undergoes an unusual intersystem crossing into an energy state of higher spin multiplicity usually a triplet state from singlet state, which then returns to the ground state.
Published in Chapter:
A Review on Chemsensors: A Versatile Tool to Detect Environmentally Toxic Metal Ions
Richa Saxena (ITM University, India) and Shweta Saxena (KRG College, India)
Copyright: © 2019
|Pages: 14
DOI: 10.4018/978-1-5225-7635-8.ch006
Abstract
Chemsensors have been playing a crucial role in various aspects of biomedical science, analytical and environmental chemistry. The toxic metal ions like Zn, Cd, Cu, Pb and Hg have increased gradually but now have reached an alarming situation, crossing the threshold value. Due to high toxicity of these heavy metals there is an obvious need for a sensor system to detect their presence. Chemsensors including surface acoustic wave sensors, enzymes, carbon nanotubes, nanoparticles, and chromophore-based sensors have attracted increasing attention over the last few years. Chemsensors prove very promising as the system is rapid, selective, sensible, low-cost, easy-to-use, and has the ability to provide real-time signals. However, recently, considerable effort has been devoted to the synthesis of sterically encumbered selenium containing species reported to display strong affinities with Hg2+ or Ag2+. This chapter reviews the basic principles involved in the design of chemsensors, their variety and applications in various established and emerging fields.