Dr Mark Blitz

Profile

I received my PhD from the University of Reading in 1990 under the supervision of Robin Walsh and Jim Baggott. I then worked as a postdoctoral fellow at the National Research Council Canada in Ottawa, with Peter Hackett. I came to Leeds in 1995 as a Postdoctoral Fellow before becoming a National Centre for Atmospheric Science (NCAS) Research Scientist in 2003. I am a member of the Atmospheric and Planetary Chemistry group in the School of Chemistry.

Research interests

My research interests are primarily in the experimental investigation of the gas-phase behaviour (kinetics and photochemistry) of species relevant to atmospheric, combustion and fundamental chemistry. These species are typically radicals, short-lived intermediates that drive change.

The chemistry observed in a particular environment is complex as it typically consists of hundreds, if not thousands, of competing processes. Therefore to understand complex phenomena it is desirable to study each process (reaction or photochemical) in isolation, and then test if each of these processes adds up to describe the observed phenomena. In the laboratory, reactions (or photochemistry) are studied in isolation, or as simple as possible, in experiments that principally use lasers, where one laser is used to create and another laser to probe the time profile of the species of interest.

I’m primarily involved in the hands-on running and maintenance of the Dainton laboratory, which has a large number of lasers that can run 6 independent experiments. Each experiment typically uses a high powered UV laser to photolyse a suitable precursor to generate the target radical. There are a number of laser schemes available for detecting the target radical, mainly via dye lasers. Laser induced fluorescence (LIF) is particularly efficient for many small species. In the atmosphere the hydroxyl radical, OH, is the principal oxidant, and it can be efficiently detected using LIF, and this is our main method to detect OH in laboratory experiments. The hydrogen atom is prevalent in combustion systems, and it can be efficiently detected at 121.56 nm, the vacuum ultraviolet, VUV. The Dainton laboratory has much experience in frequency tripling the output of a tuneable dye laser to generate VUV and detect H atom via LIF. There are a number of species that can be probed in absorption, and in one experiment the output of a lamp (200 – 800 nm) is multi-passed to provide time-resolved absorption simultaneously over all wavelengths, and is particularly efficient at detecting the Criegee intermediate, CH2OO.   

The experiments in the Dainton Laboratory are run in collaboration with Paul Seakins, Dwayne Heard and Dan Stone - and can investigate reactions over a wide range of temperatures, 30 – 1000 K, and pressures, 0.001 – 5 atmospheres. In addition, I’m a contributor to MESMER, the open source program for calculating rate coefficients through solving the chemical master equation. This program provides a direct way of linking the results from the laboratory to those from theoretical calculations, and hence is able to determine how well a given reaction is understood. It is also able to make predictions on reactions that are experimentally inaccessible.

Research groups and institutes

• Atmospheric and Planetary Chemistry