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Yusuf Hamied Department of Chemistry

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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.






Determining a Line Strength in the nu(3) Band of the Silyl Radical Using Quantum Cascade Laser Absorption Spectroscopy
AS Nave, AV Pipa, PB Davies, J Röpcke, J-PH van Helden
– J Phys Chem A
A time domain study of surfactin penetrating a phospholipid monolayer at the air-water interface investigated using sum frequency generation spectroscopy, infrared reflection absorption spectroscopy, and AFM-nano infrared microscopy
SA Goussous, AP Fellows, MTL Casford, PB Davies
– Biochimica et Biophysica Acta (BBA) - Biomembranes
Structure of the Fundamental Lipopeptide Surfactin at the Air/Water Interface Investigated by Sum Frequency Generation Spectroscopy.
SA Goussous, MTL Casford, AC Murphy, GPC Salmond, FJ Leeper, PB Davies
– The Journal of Physical Chemistry B
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
– Journal of colloid and interface science
Measurement of water vapor pressure and activity using infrared diode laser absorption spectroscopy
– Applied Spectroscopy
Applying Quantum Cascade Laser Spectroscopy in Plasma Diagnostics
J Röpcke, PB Davies, S Hamann, M Hannemann, N Lang, JPH van Helden
– Photonics
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
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
Interfacial structure of soft matter probed by SFG spectroscopy
S Ye, Y Tong, A Ge, L Qiao, PB Davies
– Chemical Record
Interfacial structure of soft matter probed by SFG spectroscopy.
S Ye, Y Tong, A Ge, L Qiao, PB Davies
– Chemical record (New York, N.Y.)
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01223 336460

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