<i>In Situ</i>Measurement of Three-Dimensional Ion Densities in Focused Femtosecond Pulses

Strohaber, James; Uiterwaal, Cornelis

doi:10.1103/physrevlett.100.023002

Cited by 34 publications

(51 citation statements)

References 21 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…A full description of this approach is found in ref. 17. We emphasize that the structures we observe (straight lines, kinks, and drops) would have escaped observation when, following common practice, ions had been recorded from the entire focal region, an approach termed 'full view' (FV).…”

Section: Eliminating Focal Averagingmentioning

confidence: 99%

“…Further details on the method used to suppress signal averaging can be found in the Appendix. By suppressing signal averaging 17 over the wide range of intensities found in the focal spot (the volume effect), we observe features in the ion yields of aromatic molecules that are fingerprints of molecular resonance-enhanced multiphoton ionization (REMPI). 18 Ionizing through an intermediate excited state allows us to study not only the ionization mechanisms, but the properties of the excited states themselves.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Ultrafast REMPI in benzene and the monohalobenzenes without the focal volume effect

Scarborough

Strohaber

Foote

et al. 2011

Phys. Chem. Chem. Phys.

View full text Add to dashboard Cite

We report on the photoionization and photofragmentation of benzene (C 6 H 6 ) and of the monohalobenzenes C 6 H 5 -X (X = F, Cl, Br, I) under intense-field, single-molecule conditions. We focus 50-fs, 804-nm pulses from a Ti:sapphire laser source, and record ion mass spectra as a function of intensity in the range B10 13 W/cm 2 to B10 15 W/cm 2 . We count ions that were created in the central, most intense part of the focal area; ions from other regions are rejected. For all targets, stable parent ions (C 6 H 5 X + ) are observed. Our data is consistent with resonance-enhanced multiphoton ionization (REMPI) involving the neutral 1 pp* excited state (primarily a phenyl excitation): all of our plots of parent ion yield versus intensity display a kink when this excitation saturates. From the intensity dependence of the ion yield we infer that both the HOMO and the HOMOÀ1 contribute to ionization in C 6 H 5 F and C 6 H 5 Cl. The proportion of phenyl (C 6 H 5 ) fragments in the mass spectra increases in the order X = F, Cl, Br, I. We ascribe these substituent-dependent observations to the different lifetimes of the C 6 H 5 X 1 pp* states. In X = I the heavy-atom effect leads to ultrafast intersystem crossing to a dissociative 3 ns* state. This breaks the C-I bond in an early stage of the ultrashort pulse, which explains the abundance of fragments that we find in the iodobenzene mass spectrum. For the lighter X = F, Cl, and Br this dissociation is much slower, which explains the lesser degree of fragmentation observed for these three molecules.

show abstract

Section: Eliminating Focal Averagingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Ultrafast REMPI in benzene and the monohalobenzenes without the focal volume effect

Scarborough

Strohaber

Foote

et al. 2011

Phys. Chem. Chem. Phys.

View full text Add to dashboard Cite

show abstract

“…Here we investigate several aromatic molecules that have been reported in the literature. Uiterwaal and his group [66][67][68] have reported ionization of several organic molecules in a micrometer-sized interaction volume and measured the time of flight in an ion mass spectrometer using 50-fs, 800-nm laser pulses. The novel feature of their setup is that it allows the measurement of ionization yields without the need to carry out volume integration.…”

Section: B Strong-field Ionization Of Large Polyatomic Moleculesmentioning

confidence: 99%

Analytical model for calibrating laser intensity in strong-field-ionization experiments

Zhao

Jin

et al. 2016

Phys. Rev. A

View full text Add to dashboard Cite

The interaction of an intense laser pulse with atoms and molecules depends extremely nonlinearly on the laser intensity. Yet experimentally there still exists no simple reliable methods for determining the peak laser intensity within the focused volume. Here we present a simple method, based on an improved Perelomov-Popov-Terent'ev model, that would allow the calibration of laser intensities from the measured ionization signals of atoms or molecules. The model is first examined by comparing ionization probabilities (or signals) of atoms and several simple diatomic molecules with those from solving the time-dependent Schrödinger equation. We then show the possibility of using this method to calibrate laser intensities for atoms, diatomic molecules as well as large polyatomic molecules, for laser intensities from the multiphoton ionization to tunneling ionization regimes.

show abstract

“…Despite the fact that even more exotic processes occur, e.g., above threshold ionization, there is still a tendency for the total number of ions to increase with increasing intensity. This is because ionization can now occur in the wings of the pulse at intensities lower than the peak intensity [12,13]. This monotonic increase is observed with simple pulse envelopes, e.g., transform-limited (TL) pulses.…”

Section: Introductionmentioning

confidence: 85%

“…Second, at high intensities, the corona of the pulse is a significant contributor to ionization, which can lead to a mixing of multiphoton and tunneling ionization, depending on where in the focus an atom is ionized. Eventually, this leads to Y ∝ (I (max) TPP ) 3/2 at very high intensities [12,13], but space charge effects due to the corona are present at lower intensities as well [41]. Regardless, a power-law dependence Y ∝ (I (max)…”

Section: A Oi-induced Ionization Modulationmentioning

confidence: 99%

Ionization enhancement and suppression by phase-locked ultrafast pulse pairs

Foote

Lin

et al. 2017

Phys. Rev. A

View full text Add to dashboard Cite

We present the results of a study of ionization of Xe atoms by a pair of phase-locked pulses, which is characterized by interference produced by the twin peaks. Two types of interference are considered: ordinary optical interference, which changes the intensity of the composite pulse and thus the ion yield, and a quantum interference, in which the excited electron wave packets interfere. We use the measured Xe + yield as a function of the temporal delay and/or relative phase between the peaks to monitor the interferences and compare their relative strengths. We model the interference with a pulse intensity function and by calculating the ionization yield with the time-dependent Schrödinger equation. Our results provide insight into optimal control pulses generated with learning algorithms. The results also show that the relative phase between peaks of a control pulse, along with small features such as distortions and imperfections in the wings of an ideal shape, play a significant role in the control process.

show abstract

In SituMeasurement of Three-Dimensional Ion Densities in Focused Femtosecond Pulses

Cited by 34 publications

References 21 publications

Ultrafast REMPI in benzene and the monohalobenzenes without the focal volume effect

Ultrafast REMPI in benzene and the monohalobenzenes without the focal volume effect

Analytical model for calibrating laser intensity in strong-field-ionization experiments

Ionization enhancement and suppression by phase-locked ultrafast pulse pairs

Contact Info

Product

Resources

About