1. Wave packet dynamics in atoms and molecules Eva Heesel Corinne Glendinning Helen Fielding Department of Chemistry University College London UCL Progress Report at RAL Attomeeting on 07.12.2005

2. Interferometer Stabilisation program completed Breadboard under investigation Ramsey Fringe Experiment Filter for wavelength selection under way Need kHz gas jet, TOF chamber, full beam line Can generate high-order harmonics from each interferometer beam + observe fringes (XUV SPIDER - Oxford report). Can also characterise bandwidth. Interferometer and Ramsey Fringes

3. Krypton experiment (Corinne) Use time-resolved photoelectron spectroscopy to look at low n Rydberg states Excitation of Kr + 4s 2 4p 5 ( 2 P 3/2 ) 6s, 7s and 5d Rydberg states from the ground state via 5p intermediate A VUV pulse will then ionise the Kr core further or ionise the Rydberg electron Relate different core excitations to core- Rydberg electron distances Double ionisation of Kr core – opportunity to study the dynamics of the Rydberg electron in the presence of a doubly charged core If photoelectrons are detected by imaging, the l- character of the Rydberg states can be reconstructed

4. 0 10 20 30 40 50 60 Energy (eV) Kr + 4s 2 4p 5 ( 2 P 3/2 ) 5p 2[3/2] J=2 11.5458 Kr + ( 2 P 3/2 ) LIMIT 13.9996 Kr + 4s 2 4p 5 ( 2 P 3/2 ) 5d 2[7/2] J=3 ; 2[3/2] J=2,1 ; 2[5/2] J=2,3 Kr + 4s 2 4p 5 ( 2 P 1/2 ) 6s 2[1/2] J=1 ; Kr + 4s 2 4p 5 ( 2 P 3/2 ) 7s 2[3/2] J=2,1 (range 13.00- 13.11 eV) Kr + ( 2 P 1/2 ) LIMIT 14.6654 Kr ++ ( 3 P 2,1,0 ) LIMITS 38.3595, 38.92338, 39.01817 Kr ++ ( 1 D 2 ) LIMIT 40.1751 Kr ++ ( 1 S 0 ) LIMIT 42.4608 1S01S0 Kr ++ 4s4p 5 ( 3 P 2,1,0 ) LIMITS 52.7330, 53.1607, 53.4289 Kr ++ (4s 2 4p 3 4 S)4d ( 5 D 0,1,2,3,4 ) LIMITS 55.5247, 55.5277, 55.5289, 55.5303,55.5498 Kr ++ 4s4p 5 ( 1 P 1 ) LIMIT 55.9499 214 nm 800 nm VUV ~6 fs OPA HHG Kr Energy levels

5. Two-stage plan for Kr experiment At UCL: Measure frequency-resolved spectrum Narrowband: Use ns beams: 214 nm and 800 nm Can do experiment both field-free and with static field (Stark splitting) Photoionise Rydberg states with 400/800 nm photon Field-free: apply field with 20 ns rise time to extract ions With static field: investigate Stark shifts (good test for imaging) (detect electrons) At IC: Measure electron dynamics + image photoelectrons Use 214 nm ns beam (OPO) and 200 nm fs beam (FHG from few-cycle pulse) Need static field for imaging.

6. Benzene experiment (Eva) Monitor ultrafast dynamics of benzene molecule using time- resolved photo- electron spectroscopy Excitation of benzene molecules from the ground state S 0 to the S 2 state with 200 nm photons (pulse duration as short as possible) The S 2 state decays very fast (< 50 fs) by internal conversion to high vibrational levels of the S 1 and S 0 states. Time-delayed probe photon (~ 50-100 eV) can ionise populations from all electronic states: Detect photoelectrons with different kinetic energy Energy resolution given by a) pulse duration (bandwidth) - 0.35 eV for 5 fs pulse b) resolution of photoelectron spectrometer (1%)

7. Benzene Energy levels S0S0 S1S1 S2S2 I.P. Energy (eV) 200 nm (6.2 eV) VUV (e.g. 50-100 eV) 4.75 6.02 9.24 VUV probe has the advantage of being able to ionise all intermediates and products

8. Plans/work in progress Generation/Characterisation of 200 nm –Generation: Fourth-harmonic of 800 nm –Characterisation: cross-correlation, two-photon ionisation,…. Calculations –Mike’s Robb group (IC chemistry) –Wave packet moves through conical intersection