1. Progress report from Leicester Stephen Ball & Mark Watkins CAVIAR spectroscopists meeting 24 Sept 2009 (Leicester University)

2. New appointment to Leicester CAVIAR postdoc: Dr Mark Watkins Research Background: Laser Spectroscopy (pulsed lasers): – Nanosecond Tuneable lasers: Radiant Dyes, Sirah, Jaguar, LaserVision IR OPO, Panther UV/Vis OPO Pump lasers: Nd:YAG(Continuum), excimer (Spectra-Physik) – Pico- and Femtosecond Tuneable solid-state OPO/OPA (TOPAS) Ti:Sapphire (Spitfire, Mai Tai), Nd:YLF (Evolution and Evolution 30) Weakly bound clusters: – Aromatic, non-aromatic, atomic chromophores – High resolution spectroscopy: REMPI, ZEKE, MATI, OODR – Small molecule and atomic solvents Equipment Design – Design, testing, commissioning and operation

3. New appointment to Leicester CAVIAR postdoc: Dr Mark Watkins Relevant expertise: Pulsed valve operation: – Bosch fuel injector valve – General Valve (series 9) Vacuum apparatus: – High vacuum operation – Turbomolecular pumps, diffusion pumps, roughing pumps – Vacuum instrumentation Raman spectroscopy (NIR region ~800 nm) – Spectracode instrumentation and CCD imager – Worked industrial patent contracts (Roche, Germany and Santrol, USA) – Developed methods towards real-time mathematical analysis of small (ppt) spectra on large background

4. CAVIAR pulsed nozzle apparatus: Up to now:No dimer signal at 620 nm (v = 5 overtone of hydrogen-bonded stretch) Not much water monomer signal at 620 nm either Detection system definitely works!: H 2 O absorptions when chamber up to atmosphere NO 2 absorption features through nozzle LED Nozzle Spectrograph/ CCD camera

5. Issue #1: v = 5 dimer overtone is v weak Solution: Move to v = 4 overtone around 760 nm (expected x10 stronger) Progress:Done! LED BBCEAS spectra: 70 nm bandwidth, mirror reflectivity calibration Mirror Curve (1200 lines/mm grating, centred at 765 nm)Low resolution spectrum of CO 2 “Venus bands” at 782.8 and 789.1 nm 10 km path length in 1 m cavity

6. Issue #2: Spatial overlap of nozzle expansion with light beam Solution: Point nozzle  slit expansion Progress:Done! beampath Slit width = 12 mm Diameter ~ 350  m

7. Issue #3: H 2 O number density in source gas before: P sat (H 2 O) = 20 Torr and >1 atm N 2 bath gas Solution: Heated nozzle source ~ 60  C after: 150-250 Torr H 2 O + 0.5-1.0 atm N 2 Progress:Heated H 2 O source built, waiting on thermostat electronics H 2 O reservoir General Valve thermal body heating collar thermocouple

8. Issue #4: Temporal overlap of nozzle expansion with light beam Current LED-BBCEAS detection methodology is CW Solution: Pulsed detection methodology: Cambridge BBCRDS system Pulsed laser and clocked CCD camera synchronised to nozzle Progress:Equipment loan arranged for October  LED-BBCEAS Pulsed nozzle Pulsed laser BBCRDS Pulsed nozzle Pulsed nozzle: rep rate 20 Hz, 180 – 300  s opening time

9. Photoacoustic Experiment? Pulsed IR laser (OPO/OPA) Water vapour spectrum (taken in air) Timescale: 1 – 3 days Oscilloscope

10. SeptOctNovDecJanFebMarAprAfter  Characterise NIR mirrors (730- 780 nm) for  = 4 at 755 nm Finish electronics for heated nozzle source Optimise slit nozzle conditions for making dimer & for chamber’s pumps Modification of nozzle design (if necessary) LED-BBCEAS measurements in the  = 4 region Locate dimer feature Commission Nd:YAG laser Experiments with Cambridge BBCRDS detection system delivery Characterise IR mirrors (910- 1000nm) for  = 3 at 960 nm: LED-BBCEAS experiments in the  = 3 region Write up work Shillings et al Timetable for experimental work @ Leicester