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Professor Paul Davies

Portrait of pbd2

Laser Spectroscopy has revolutionised the determination of molecular structure. The Cambridge Infrared Laser Spectroscopy Group uses a variety of novel laser based techniques to study molecules in situations as diverse as low pressure electric discharges (plasmas) and on surfaces buried under liquids. The shapes of short lived molecules like free radicals and ions are precisely determined using solid state diode lasers in combination with sensitive, species- specific detection methods like Velocity Modulation. Recent diode laser spectroscopy of free radicals has included measurement of the band strength of the methyl radical, CH3. This is required for detection and density measurements of CH3 in the atmospheres of the giant planets Saturn and Neptune. We are now enhancing the sensitivity of IR laser absorption spectroscopy in a fruitful collaboration with German colleagues using a Cavity Ring Down (CRD) spectrometer built around novel Quantum Cascade Lasers. The group is also heavily involved in non linear laser spectroscopy particularly the interface specific technique of Sum Frequency Generation (SFG). We use SFG to gain insight into adsorption at interfaces on a molecular scale e.g. of surfactants and polymers. We use nano and picosecond lasers for SFG in Cambridge and femtosecond SFG to quantify non linear optical effects in Langmuir Blodgett films in a joint project with co-workers in Hokkaido, Japan. The aim is eventually to use SFG to study biological systems like the lung surfactants. In addition to our international projects, which involve overseas visits by our research students, much of our work on surfaces and interfaces is strongly supported by industry.

 

 

 

 

Publications

A structural and temporal study of the surfactants behenyltrimethylammonium methosulfate and behenyltrimethylammonium chloride adsorbed at air/water and air/glass interfaces using sum frequency generation spectroscopy.
SA Goussous, MTL Casford, SA Johnson, PB Davies
– J Colloid Interface Sci
(2017)
488,
365
The Adsorption of Synovene on ZDDP Wear Tracks: A Sum Frequency Generation (SFG) Vibrational Spectroscopy Study
MTL Casford, PB Davies, TD Smith, GL Bracchi
– Tribology Letters
(2016)
62,
ARTN 11
High resolution spectroscopy of silane with an external-cavity quantum cascade laser: Absolute line strengths of the ν3 fundamental band at 4.6μm
JH van Helden, D Lopatik, A Nave, N Lang, PB Davies, J Röpcke
– Journal of Quantitative Spectroscopy and Radiative Transfer
(2015)
151,
287
Interfacial structure of soft matter probed by SFG spectroscopy
S Ye, Y Tong, A Ge, L Qiao, PB Davies
– Chemical Record
(2014)
14,
791
The structure of lipid bilayers adsorbed on activated carboxy-terminated monolayers investigated by sum frequency generation spectroscopy
MTL Casford, A Ge, PJN Kett, S Ye, PB Davies
– J Phys Chem B
(2014)
118,
3335
On recent progress applying quantum cascade lasers in plasma diagnostics
JH van Helden, PB Davies, M Hübner, N Lang, A Rousseau, S Welzel, J Röpcke
– Optics InfoBase Conference Papers
(2014)
Interfacial structure of soft matter probed by SFG spectroscopy.
S Ye, Y Tong, A Ge, L Qiao, PB Davies
– Chemical Record
(2014)
14,
791
Sum Frequency Generation Vibrational Spectroscopy of Cholesterol in Hybrid Bilayer Membranes
PJN Kett, MTL Casford, PB Davies
– J Phys Chem B
(2013)
117,
6455
Effect of multiple group orientations on sum frequency generation spectra
PJN Kett, MTL Casford, PB Davies
– Molecular Physics
(2013)
111,
173
SFG characterization of a cationic ONLO dye in biological thin films
LE Johnson, MT Casford, DL Elder, PB Davies, MS Johal
– Proceedings of SPIE - The International Society for Optical Engineering
(2013)
8817,
UNSP 88170P
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Research Group

Telephone number

01223 336460

Email address

pbd2@cam.ac.uk