Chemical Processes & Instrument Development: Instruments
Supporting Instrumentation
Excimer Photolysis Lasers
Excimer or exciplex lasers are gas lasers using a combination of noble gases (Xe, Kr, Ar, Ne) and reactive halogen gases (Cl2, F2) as the lasing medium. Under high gas pressures and electrical discharges, an excited pseudo-molecule called an excimer or exiplex is created. The dissociation/relaxation of the excimer/exciplex pseudo-molecule generates laser light. Excimer lasers produce large pulse energies (tens to hundreds of millijoules per pulse) at various pulse frequencies (one to hundreds of pulse(s) per second).
Common Wavelengths
193 nm (ArF)
248 nm (KrF)
308 nm (XeCl)
355 nm (XeF)
Typical Species Photolyzed
193 nm: HNO3, halogenated compounds e.g. CF3C(O)Cl
248 nm: H2O2, HNO3, (CH3)3COOH for OH generation; (COCl)2 for Cl generation
355 nm: Cl2 for Cl generation; HONO
Pulse widths
~10-50 ns
Pulse Energy
up to 800 mJ/pulse depending on laser and laser wavelength
Applications
PLP-LIF
PLP-RF
Photolysis yield determination
Nd:YAG Pumped Dye Probe Lasers
Dye-laser, specifically the continuum ND-6000 dye laser system, is a narrow bandwidth, high energy output system capable of a tuning range spanning from 420 to 900 nm. The ND-6000 dye lasers can be pumped with various Nd:YAG lasers at 355 or 532 nm (frequency tripled and doubled 1064nm light)
Quantel Brilliant B Pulsed Nd:YAG laser
Specs:
10 Hz rep rate
5 ns pulse width
400 mJ/pulse
532 nm output (frequency doubled)
Quanta-Ray Lab Pulsed Nd:YAG Laser
10 Hz rep rate
1-2 ns pulse width (532nm)
~200 mJ/pulse (532nm)
532 nm output (frequency doubled)
Continuum Surelight Pulsed Nd:YAG Laser
Specs:
10 Hz rep rate
4-6 ns pulse width
~200 mJ/pulse (532 nm)
532 nm output (frequency doubled)
ND-6000 Specifications
Output Energy: up to 260 mJ/pulse
Accuracy: +/- 0.05 nm
Bandwidth: 0.05 cm-1 @560 nm with dual grating
Applications
CRDS (probing NO3 radicals), LIF (probing OH, OD radicals)
Gas Handling System
The gas handling manifold is used for the preparation of gas samples/mixtures with precise mixing ratios for a variety of applications, including UV/FTIR cross section determination and absolute and relative kinetics measurements. The apparatus is also used for other regular laboratory applications such as degassing, vacuum distillation of procured compounds.
