Instrumentation in the Molecular Physics Group Presented by: Mats Larsson

Experimental research activities Electron-driven molecular processes Ultrafast chemical physics Spectroscopy of clusters (Microwave induced chemistry) (Linear ion trap) (Biomedical imaging)

Electron-driven molecular processes The problem of producing quantum systems (i.e. molecules) in well defined states How to produce ionized biological molecules in the gas phase How to detect reaction products of electron- driven processes How to obtain chemical information

State selected molecular ions ABC + ( , v, J) How do we control the internal quantum states? Excitations can be removed by storage of ABC + in CRYRING. This does not always work for J This does not work for molecules of type A 2 + This does not work if we want to study ABC + in a known distribution of excited quantum states

Pinhole discharge source Designed and built at UC Berkely Characterized at UC Berkeley Shipped to Stockholm for experiment at CRYRING Shipped back to Berkeley, redesigned, and characterized Shipped to Stockholm for new experiment

High pressure Vacuum Laser beam for probing Supersonic expansion including ions and neutrals Discharge

Energy level structure of H 3 +

Interstellar transitions 2 0 ortho para

Diffuse cloud absorption

Control of vibrational excitation Electron-impact source Built and characterized at SRI International in Menlo Park, CA Shipped AMOLF in Amsterdam and then later to Stockholm

Repeller plates Extraction Plate Deflection plates Hot filament (outside the source) Electron Trap Gas Inlet Ground Plate

Better control over vibrational populations –Experiments on SEC and DR –More control over ion source settings AMOLF & SRI, Phil Cosby –O 2 + ( ) + Cs  O 2 *(Ryd,n=3, ’= )  O + O + KER(0-3eV, ) CRYRING –O e -  (O 2 *(Ryd)  ) O 2 **  O + O + KER V=0! V=0,1,2,3! Ion Source Developments

Biological molecules In the gas phase

Spray needle : The needle is inside a nitrogen- gas filled housing for spray stability. Entrance capillary: The ion droplets are passing through a heated capillary and evaporate.

Exit: After the capillary, the ions are stored and pulsed by a hexapole trap.

experiment Interaction of biomolecular ions with electrons/photons Ion trap Electrospray unit with a pulsed hexapole trap Quadrople mass filter

MCPs and phosphor screen H O H CCD- camera Beam splitter Timing (Camac) Image intensifier PC 16-segmented PMT

Experimental parameters Data taking rate: Hz Time resolution: ns Energy resolution: 100 meV No chemical information in the standard set-up

Specifications Data taking rate > 10 kHz Time resolution  1 ns Position resolution  0.1 mm Dead area 1 cm 2 No chemical information

probe (wlc) sample flow cell polychromator CCD pump (shg, thg, topas) Example: I 2 Br - + h  I Br I 2 Br - /CH 3 CN  +

The Cluster Apparatus

The total cluster machine assembly, combining a laser ablation source with a time-of-flight mass spectrometer Pressure: – torr inside the machine The extracting electric field: static in Stark spectroscopy switched in lifetime measurements Cold molecules (T trans < T rot < T vibr < T electr )  only lowest vibrational and electronic states populated

Nd:YAG laser (1064 nm) for ablation of the metal clusters A tunable ring-dye laser, pumped by an Ar + laser, for exciting the molecules. The narrow bandwidth cw laser light (FWHM ~ 1 MHz) is pulsed-amplified in a Bethune cell, pumped by a XeCl excimer laser (308 nm)  pulses 10 ns, ~1  J, FWHM < 150 MHz An ArF excimer laser (193 nm) for ionizing the molecules Operating frequency: 10 Hz Auto-scan system. Iodine calibration spectrum.

Conclusions The ion source R&D is probably too specialized to be of interest for an AlbaNova instrumentation project The electro-optical part is covered by the KAW application From the Molecular Physics point of view, detector development is most suited