Femtosecond time-resolved second-harmonic generation at the surface of alkali metal clusters

Simon, Matthias; Träger, F.; Assion, A.; Lang, B.; Voll, Sabine; Gerber, G.

doi:10.1016/s0009-2614(98)01073-2

Cited by 35 publications

(41 citation statements)

References 21 publications

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“…The limited mean free path of the electrons makes photoemission surface sensitive, but in general less than in the case of SFG. In both SFG and 2PPE interference effects [1,3,8,[11][12][13] appear, which our theory allows us to study. Of course, these interference effects are expected to depend on the pulse shapes.…”

Section: Introductionmentioning

confidence: 79%

“…Since the system is in a superposition of two eigenstates, the polarization oscillates with the frequency (E k l − E k l )/h, as follows from the first exponential in the parentheses in equation (10). Such superpositions are described by the off-diagonal components of the density matrix 3 . The diagonal components denoting the occupation numbers of states are not changed by a single absorption.…”

Section: Sum-frequency Generationmentioning

confidence: 99%

“…After the emission the electron is again in the pure eigenstate 2 If |k l is a state in the Fermi sea then the first term in equation (10) corresponds to the process shown in figure 1, whereas in the second one an electron from deep below the Fermi energy is excited by the second interaction into the hole left by the first interaction. 3 Obviously the system could now emit a photon at the oscillation frequency. This is the linear optical response described by χ i j .…”

Section: Sum-frequency Generationmentioning

confidence: 99%

“…For simplicity we talk about SFG in the following, although difference-frequency generation is automatically included in our theory. Time-resolved measurements [1][2][3][4][5] usually employ the pump-probe technique, where two laser pulses of the same (single-colour) or different (twocolour) frequency are applied with a time delay T between them. This time delay controls the time between the two absorptions and thus the relaxation dynamics of the electron in the intermediate state |2 is crucial; see figure 1.…”

Section: Introductionmentioning

confidence: 99%

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Response theory for time-resolved second-harmonic generation and two-photon photoemission

Timm

2004

J. Phys.: Condens. Matter

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A unified response theory for the time-resolved nonlinear light generation and two-photon photoemission (2PPE) from metal surfaces is presented. The theory allows one to describe the dependence of the nonlinear optical response and the photoelectron yield, respectively, on the time dependence of the exciting light field. Quantum-mechanical interference effects affect the results significantly. Contributions to 2PPE due to the optical nonlinearity of the surface region are derived and shown to be relevant close to a plasmon resonance. The interplay between pulse shape, relaxation times of excited electrons, and band structure is analysed directly in the time domain. While our theory works for arbitrary pulse shapes, we mainly focus on the case of two pulses of the same mean frequency. Difficulties in extracting relaxation rates from pump-probe experiments are discussed-for example due to the effect of detuning of intermediate states on the interference. The theory also allows one to determine the range of validity of the optical Bloch equations and of semiclassical rate equations, respectively. Finally, we discuss how collective plasma excitations affect the nonlinear optical response and 2PPE.

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Section: Introductionmentioning

confidence: 79%

Section: Sum-frequency Generationmentioning

confidence: 99%

Section: Sum-frequency Generationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Response theory for time-resolved second-harmonic generation and two-photon photoemission

Timm

2004

J. Phys.: Condens. Matter

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“…Similarly, we have to exclude the excitation of optical phonons from the consideration, as these phonons usually have much higher frequencies [47,48]. In the same way plasmonic excitations can not be responsible for the observed oscillations, firstly due to their higher frequency [49,50] and secondly, due to the extremely short lifetime of a localized plasmon which can be down to a few femtoseconds [51][52][53][54]. Also, additional experiments with various wavelengths of the probe beam demonstrated no significant difference in the magnitude of the effect.…”

Section: Long Time Rangementioning

confidence: 99%

Femtosecond laser-induced optical anisotropy in a two-dimensional lattice of magnetic dots

et al. 2014

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Using pump-probe optical polarimetry we demonstrate that femtosecond laser excitation of a 2D regular lattice of magnetic nanodots effectively changes the optical anisotropy of the array. Study of the dynamics of the femtosecond laser-induced anisotropy reveals four main mechanisms occurring in the electronic, spin, and lattice subsystems. Below 1 ps, a strong Kerr-like nonlinearity causes linear birefringence, with its axis directed along the electric field of the linearly polarized femtosecond laser pump pulse. In addition, a long-living linear birefringence is also induced due to slowly relaxing excitations. Also below 1 ps, ultrafast laser-induced demagnetization of Co leads to a partial breakdown of the circular birefringence of the magnetic nanodots. On the timescale up to 300 ps, optically triggered acoustic modes of the dots drive oscillations of the linear optical birefringence. During this process, the oscillations damp while transferring their energy into acoustic modes of the substrate. On the nanosecond timescale, the signal is dominated by acoustic oscillations at the surface of the substrate.

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Second-Harmonic Diffraction from a Transient Population Grating of Silicon Dangling Bonds

Voelkmann

Mauerer

Berthold

et al. 1999

phys. stat. sol. (a)

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A surface sensitive purely optical technique is demonstrated for the investigation of rapid dephasing processes of excited electronic surface states. The combination of degenerate four‐wave‐mixing (DFWM) with second‐harmonic generation (SHG) can be employed to measure the diffracted second‐harmonic signal from a transient population grating of Si(111)7×7 dangling‐bond states. By this five‐wave‐mixing process, which is described by a χ(4)‐tensor and is thus dipole‐forbidden in bulk silicon, we deduce decoherence times of ∼5 fs.

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Femtosecond time-resolved second-harmonic generation at the surface of alkali metal clusters

Cited by 35 publications

References 21 publications

Response theory for time-resolved second-harmonic generation and two-photon photoemission

Response theory for time-resolved second-harmonic generation and two-photon photoemission

Femtosecond laser-induced optical anisotropy in a two-dimensional lattice of magnetic dots

Second-Harmonic Diffraction from a Transient Population Grating of Silicon Dangling Bonds

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