An STM Measures I(r) Tunneling is one of the simplest quantum mechanical process A Laser STM for Molecules Tunneling has transformed surface science. Scanning the field around the molecule is like scanning the tip across a surface -- a molecular STM

H 2 ionization in circularly polarized light e p The electron direction determines the field direction at the moment of ionization The bond softened ion determines the molecule’s direction at the moment of ionization

COLTRIMS – measuring the 3d-momenta of correlated particles

PRL 102, (2009) The angle-dependent ionization probability

Implications of high tunneling rates: “DC” tunneling – The exponent is ~ A small change in E i is highly leveraged by the large E a /E(t). Laser tunneling: -- The exponent is ~ 8. The leverage is weakened. Lower orbitals will contribute.

PRL 94, (2005) Measuring excited states

The laser STM senses the structure of orbitals: SU1 – direct tunneling SU2 – excitation by bound state interaction with the departing electron  IP~4 eV

Applying the “laser STM” to HCl

Deeper orbitals tunnel ionize (directly)

HCl Two or more orbitals can ionize

Transient alignment of molecules time Phys. Rev. A. 68, (2003)

A molecular STM has much more information

Normalized Differences Notice: 1 Low lateral momentum structures – tunneling and 2 High lateral momentum structures – elastic scattering Science (2008)

 p molecule p normal laser The Model: 1.Assume 2.Propagate swarm of electron trajectories classically 3.Including electron-ion interaction 4.Include alignment distribution

Low Lateral momentum electrons Science (2008)

N2N2 O2O2 CO 2 PRL 98, (2007) The angle dependent probability

Transparent Solids:  E = O(10eV) a b c  -SiO 2 Al 2 O 3 LiF crystal structure

Extending to Solids? The Lawn Mower Model Self-controlled energy deposition. electron and energy density is predicted. Opt. Express 13, 3208 (2005).

Transmission as a function of angle

Angle dependent changes in the reduced-mass change the ionization rate. ( /2) ~  m 3 resolution

crystalline fused Only the focal region is measured Phys. Rev. Lett. 101, (2008) 0 amorphous crystal

The laser STM Atoms: The filter function using circular polarization. Molecules: The orbital Filtered image of the orbital Quantify the contribution of lower orbitals. Solids: The reduced tunneling mass Measuring crystal symmerty Link to HHG – correlated measurements

A mixture of optical and collision science Coherence can be transferred several times between electrons and photons The mixture offers new opportunities for each To optics -- Angstrom spatial imaging. To collision physics -- Time resolution. Bertrand P1, Wörner P3, Meckel

Three new forms of nonlinear spectroscopy 1Tunneling (to characterize orbitals) 2Elastic scattering or Laser Induced Electron Diffraction (to determine nuclear positions) – see Meckel et al. 3Interferometry (to image orbitals -- photoelectron spectroscopy in reverse) – see poster by Bertrand P1 and Wörner P3

The tunneling electron wave packet of O 2