The impact of the carrier envelope phase-dependence on system and laser parameters

Abstract

Abstract. We investigate, from a theoretical perspective, photo-emission of electrons induced by ultra-short infrared pulses covering only a few photon cycles. In particular, we investigate the impact of the Carrier-Envelope Phase (CEP) of the laser pulse which plays an increasingly large role for decreasing pulse length. As key observable we look at the asymmetry of the angular distribution as function of kinetic energy of the emitted electrons. The focus of the present study lies on the system dependence of the reaction. To this end, we study two very different systems in comparison, an Ar atom and the Na + 9 cluster. The study employs a fully quantum-mechanical description of electron dynamics at the level of Time-Dependent Density Functional Theory (TDDFT). We find a sensitive dependence on the system which can be related to the different spectral response properties. Results can be understood from an interplay of the ponderomotive motion driven by the external photon field and dynamical polarization of the system.

Far Off Equilibrium Dynamics in Clusters and Molecules

“…The full width at half maximum of intensity (FWHM) is given as FWHM ≃ T pulse /3. The parameter φ CEP , the so-called carrier-envelop phase, is the phase between the maximum of an oscillation at frequencyhω las and the maximum of the cos 2 envelope which plays a role particularly for short pulses [29].…”

“…The 1.8 eV laser frequency lies far below any considerable dipole strength for Ar while it comes close to the strong Mie plasmon resonance for the Na cluster. For a detailed discussion with more material see Reinhard et al [29].…”

Probing electron dynamics by IR+XUV pulses

“…The standard pulse parameters used throughout this paper are: IR frequency ω IR = 0.1 Ry corresponding to cycle time τ IR = 3.04 fs; IR pulse length T IR = τ IR ; XUV frequency ω X = 3 Ry; XUV pulse length T X = τ IR /6 = 0.51 fs which means 5 XUV cycles in the pulse. Because of the short IR pulse length T IR = τ IR the Carrier Envelop Phase (CEP), namely the phase of the oscillatory pattern with respect to pulse envelop, acquires a large influence [23][24][25]. We shall briefly discuss its impact in Section 2.3.…”

“…Ionization can be measured as such or energy resolved as in Photo-Electron Spectra (PES) [17][18][19][20] or even in an angular/energy resolved manner [11]. The (energy integrated) Photo-emission Angular Distribution (PAD), is also a fruitful observable [21,22], which is known to deliver interesting information already for femtosecond pulses [23][24][25].…”