Search results
Results from the WOW.Com Content Network
Dobson spectrophotometers can be used to measure both total column ozone and profiles of ozone in the atmosphere. [5] [6] Ozone is tri-atomic oxygen, O 3; ozone molecules absorb harmful UV light in the atmosphere before it reaches the surface of the earth. No UVC radiation penetrates to the ground as it is absorbed in the ozone-oxygen cycle.
An ozone monitor of this type operates by pulling an air sample from the atmosphere into the machine with an air pump. [3] During one cycle, the ozone monitor will take one air sample through the air inlet, and scrub the ozone from the air; for the next cycle, an air sample bypasses the scrubber and the ozone value calculated.
Instrument Uses Autopsy table: Corpses undergoing autopsy are placed here. CO 2: for preservation of the corpse Dissection scissors: Dissection scissors are used in autopsy to cut open body tissues.
In a photoionization detector, high-energy photons, typically in the vacuum ultraviolet (VUV) range, break molecules into positively charged ions. [2] As compounds enter the detector they are bombarded by high-energy UV photons and are ionized when they absorb the UV light, resulting in ejection of electrons and the formation of positively charged ions.
Other compounds can also be determined by this method (ozone, N-oxides, S-compounds). A typical example is NO determination with detection limits down to 1 ppb. Highly specialised chemiluminescence detectors have been used recently to determine concentrations as well as fluxes of NO x with detection limits as low as 5 ppt. [14] [15] [16]
There are three general categories in which forensic science uses trace evidence. It can be used for investigative aids, associative evidence, and in-scene reconstructions. [ 3 ] In terms of investigative aids, trace evidence can provide information to determine the origin of a sample and determine the manufacture date of the material, all of ...
The detection limit for electron capture detectors is 5 femtograms per second (fg/s) and the detector commonly exhibits a 10,000-fold linear range. [ citation needed ] This made it possible to detect halogenated compounds such as pesticides and CFCs , even at levels of only one part per trillion ( ppt ), thus revolutionizing our understanding ...
Schematic of a solid-state detector. The operating principle of Semiconductor detectors is similar to gas ionization detectors: except that instead of ionization of gas atoms, free electrons and holes are produced which create a signal at the electrodes. The advantage of solid state detectors is the greater resolution of the resultant energy ...