Intense laser field interaction with molecular ions Daniel Strasser Institute of Chemistry Hebrew University of Jerusalem Batsgeva De Rothschild Seminar 2012 Ultrafast laser – molecular ion lab 2013 Ultrafast EUV Probe Project time Oct 2009 2011

for Molecular Reaction Dynamics Ultrafast EUV Probe for Molecular Reaction Dynamics Time resolved single photon Coulomb explosion imaging

e- - molecule reactions exhibit extremely non-B.O. dynamics example: ECD of Biomolecules ( Electron Capture Dissociation ) R-N+H3 + e- (R-NH3)•* superexcited state R-NH2 + (H•)hot R• + NH3 R.A. Zubarev et al. EJMS (2002)

e- - molecule reactions are everywhere Molecular cloud Barnard 68 European Southern Observatory: Alves, J. F., Lada, C. J., and Lada, E. A. example: Dissociative Recombination of molecular ions e- H3+ superexcited H3 state 10 5 H3+ DR (fragment imaging) D. Strasser et al. PRL (2001)

Time resolved probing of e- – molecule reactions New basic insights beyond B.O. into chemical reactions

Can we time resolve e- – molecule dynamics ? Need Ultrafast EUV Photons AB+ + e- AB** (SES) AB + hn A + B*

Ultrafast EUV shources: Accelerator based FEL facilities: ( LCLS, FLASH, …) table top HHG sources: “simply” focusing intense IR into rare gas ~5x1014 W/cm2 in 10 PSI Ar ≥ 106 photons/15th/pulse

Ultrafast SES dynamics N2+ + e- N + N* N2 + hn Pump: 53.7 nm Probe: 800 nm Ultrafast Predissociation time ≤ 25 fs short lived N* (3d or 4p) D. Strasser et al. Mol. Phys. (2008) at Berkeley with Steve Leone

Anionic Superexcited States AB + e- NIR-VIS photons AB**- (SES) AB- + hn A- + B* other advantages: mass selectivity fast beam fragment imaging

My Dream

and now with Coherent Control …

Laser system: Mai-Tai Oscillator Spitfire Amplifier ------------------------- < 25 fs < 4 mJ/pulse @ 1kHz OPA-800 oscillator amplifier Pulse Shaper ----------------------------- 128 spectral pixels of phase & amp. control

Fast beam fragment imaging shaped ultrafast, or pump-probe pulses imaging detector measure molecule { vi } vbeam {xi, yi, ti } ~1,000,000 m/s L t ~ ns x ~ cm Coincidence detection of all possible products: Cations, Anions, Neutrals and electrons

Fast beam fragment imaging shaped ultrafast, or pump-probe pulses imaging detector measure molecule { vi } vbeam {xi, yi, ti } ~1,000,000 m/s L mass gate electrodes pulsed ion beam

Fast beam fragment imaging ultrafast pump-probe pulses imaging detector measure molecule { vi } vbeam {xi, yi, ti } ~1,000,000 m/s L Experiments that are now possible: -Photodetachment, Photodissociation -Intense laser field – anion interaction -Pulse shaping, Coherent control and more -Coulomb explosion -Pump-Probe : Time resolve SES dynamics

test: H2O- photodetachment Water ion clusters Unfocused laser (H2O) 17- Photodetachment ( neutral products )

in situ measurement of the volume effect probed with linear photodetachment z Turns out that its valuable to do this in situ since otherwise un-noticable self focusing in the entrance window can shift the focal point. Ion beam

Calculated Peak Intensities z Turns out that its valuable to do this in situ since otherwise un-noticable self focusing in the entrance window can shift the focal point. Ion beam

linear photodetachment modeling of the volume effect z Turns out that its valuable to do this in situ since otherwise un-noticable self focusing in the entrance window can shift the focal point. Ion beam

1st model system: SF6 + e- SF6- studies will be extended to SF6 , H2O, and Ar based clusters

1st model system: SF6 + e- U SF6 SF5- +F ~3eV SF6- ~1.1eV 1.57 Å R ( S-F ) U SF6- SF6 1.73 Å 1.57 Å SF5- +F ~3eV ~1.1eV

SF6- Energetics Neutral yield [a.u.] hv [eV] e- Photodetachment efficiency curve (PDE) measurement with tunable wavelength ns laser (in collaboration with Oded Heber WIS) Neutral yield [a.u.] hv [eV] ΔEv ~ 0.1 eV

SF6- Energetics e- Photodetachment efficiency curve (PDE) measurement with tunable wavelength ns laser (in collaboration with Oded Heber WIS) 800 nm

SF6- non-linear photodetachment ~40 fs 800 nm balance between peak intensity and volume effect (~2×1014 W/cm2 ) z Ion beam

SF6- non-linear photodetachment @800nm peak intensity (~6×1014 W/cm2 )

Can we remove more than one electron ? 3 Step model for intense field interaction with neutral species (1) (3) And is this picture at all useful for anions ?

To remove the next electron we need >10 more photons SF6 Dissociative Ionization data Ion AE (eV) Method F+ 37.5 ± 1.0 EI FS+ 30.5 ± 0.5 F2S+ 27.0 ± 0.3 F3S+ 18.79 ± 0.14 PI F4S+ 19.1 ± 0.5 F5S+ 15.32 ± 0.04 NIST chemistry webbook No one was able to observe a stable SF6+

Double detachment observed @ 5x1014 W/cm2

higher order processes – double detachment SF6- products @ I ≥ 1015 W/cm2 SIMION simulation SF+ SF2-5+ S+ F+ SF6+ neutrals

higher order processes – double detachment SF6- products @ I ≥ 1015 W/cm2 SIMION simulation add 1eV KER SF+ SF2-5+ S+ F+ SF6+ neutrals

Polarization F+ emitted along TOF axis

originate from Coulomb explosion events Correlated F+ and S+ originate from Coulomb explosion events Neutrals RG background S+ F+ F+

Chirp effect ? F+ Neutrals

TOD effect ? F+ Neutrals

Polarization effect ?

Students: Non-linear detachment :Yishai Albeck PDE curve measurements: Itamar Luzon Collaborations: Oded Heber (Weizmann ) Ori Cheshnovsky (TAU) Funding: ERC Legacy Heritage fund (מורשה) EU PF7 people program (MC IRG) Farks center for light induced processes James Franck fund (light matter interactions)

M.Sc., Ph.D., and Postdoc positions available Ultrafast Laser Pulses Time Resolved Dynamics Funding: ERC Legacy Heritage fund (מורשה) EU PF7 people program (MC IRG) Farks center for light induced processes James Franck fund (light matter interactions)