zhao_2023 ========= X\. Zhao, T\. Xu, X\. Yu, D\. Ren, M\. Li, X\. Zhang, X\. Li, P\. Ma, D\. Zhang, C\. Wang, Q\. Wang, X\. Hu, S\. Luo, Y\. Wu, J\. Wang and D\. Ding, "Probing electron localization during molecular dissociation by femtosecond strong\-field ion momentum spectroscopy", Commun\. Phys\. 6, 124 \(2023\) `Source record `__ · :doc:`Catalogue ` · :doc:`Review register ` DOI: `10\.1038/s42005\-023\-01248\-3 `__ **Source kind:** measurement **Recorded technique:** Strong\-field pump, strong\-field probe ion momentum spectroscopy of N2O in a COLTRIMS \(16\.9 V/cm extraction, delay\-line detector\)\: an 800 nm, ~35 fs pump, linear, 1\.0 x 10^14 W/cm2, ionises N2O to N2O\+ \(B 2Pi\); an elliptical probe \(epsilon ~ 0\.7, 3\.5 x 10^14 W/cm2\) ionises the dissociating cation to N2O2\+, and the coincident NO\+ \+ N\+ and N2\+ \+ O\+ pairs give the kinetic energy release against delay \(to 6 ps; cross\-correlation 90 fs FWHM\)\. Semiclassical Landau\-Zener surface\-hopping trajectories on CASSCF potential surfaces for comparison \(Methods, p\. 6\)\. **Materials in structured entries:** N2O **Dataset quantities:** dissociation\_time, kinetic\_energy\_release **Contents:** 6 datasets; 0 formulas. Curation notes -------------- Commun\. Phys\. 6\:124 \(2023\), pdf pages 1\-7\. Identity checked on pdf page 1 \(title, authors, '\(2023\) 6\:124', DOI\)\. Same group and apparatus as zhao\_2020\. The supplementary information \(Supplementary Notes 1\-3, Figs\. 1\-4\: the rise times of the two channels, the trajectories\) is not in the library\. THE MEASUREMENT AND ITS KER \(pp\. 2\-4; TC\-971\)\. The probe's Coulomb explosion KER of the dissociating cation is KER\(t\) = E0 \+ E\_cou\(t\), E\_cou = 1/R\(t\) \(atomic units\), with E0 'the initial KER from the dissociation of the B 2Pi state' \(p\. 3\)\. One branch of the coincident KER is constant \(direct double ionisation by one pulse\); the other falls 'to asymptotic energies of 0\.6 eV for the NO\+ \+ N\+ channel and 0\.4 eV for the NN\+ \+ O\+ channel at a delay time of 6 ps' \(p\. 3\); the simulation gives 1\.1 eV and 0\.5 eV, the difference ascribed to the neglect of the fragments' vibrational and rotational energy \(pp\. 3\-4\)\. 'Both the experiments and simulations demonstrate that the KER decreases rapidly in the first ps \.\.\. The KER reaches the dissociation energy for both channels at around 1 ps, suggesting that the ultrafast dissociation of both channels is complete within the first ps' \(pp\. 3\-4\)\. Selection windows\: 0\.5\-5\.0 eV \(NO\+ \+ N\+\), 0\.3\-4\.6 eV \(NN\+ \+ O\+\) \(p\. 2\)\. DOUBT \(TC\-971\)\: the 6 ps value includes the residual Coulomb energy 1/R at the probe; the paper gives R = 140 a\.u\. at 1500 fs for N\-NO\+ \(p\. 4\), where 1/R is 0\.19 eV, and R at 6 ps is not stated, so the asymptotes are upper bounds to E0 by an amount not given\. No uncertainty is printed\. STATE ASSIGNMENTS \(pp\. 2\-4\)\: the pump populates B 2Pi, most likely by tunnelling from HOMO\-1 to A 2Sigma\+ followed by excitation within the pulse \(HOMO\-2 negligible\); B 2Pi couples through conical intersections to 2Delta states and dissociates to NO\+ \+ N\(2D\) \(2pi \-\> 8sigma\) or NN\+ \+ O\(3P\) \(7sigma \-\> 3pi\) \(Fig\. 2, p\. 4\)\. NOT TAKEN\: the asymmetries of the ion sum momentum \(Figs\. 1, 4\), which carry the paper's electron\-localisation result; the calculated dipole\-moment differences \(Fig\. 4c, d\)\. Figures for later \(TC\-971\)\: Fig\. 3\(a, c\), the measured KER against delay \(raster maps with vector axes\), for the time dependence; Fig\. 1\(c, f\) \(vector\)\. **Recorded bibliographic identity status:** VALIDATED. This concerns identification of the source; it does not establish the scientific correctness of its contents. Datasets -------- zhao\_2023/ker\_NOplus\_N ~~~~~~~~~~~~~~~~~~~~~~~~~ .. code-block:: text { "id": "ker_NOplus_N", "material": "N2O", "table": "text", "quantity": "kinetic_energy_release", "unit": "eV", "abscissa": "none", "use": "primary", "parameters": { "channel": "N2O+ -> NO+ + N(2D)", "kind": "asymptotic", "state": "N2O+ B 2Pi (assigned)", "wavelength_nm": 800, "pulse_fs": 35, "polarization": "linear", "intensity_w_cm2": 100000000000000.0 } } 1 inline points in the source record. p\. 3 \(TC\-971\)\: the asymptote at 6 ps of the delay\-dependent KER of the NO\+ \+ N\+ pairs, taken by the paper as the dissociation's own KER E0 plus a residual Coulomb energy; an upper bound to E0 \(the record's doubt\)\. Pump 800 nm, ~35 fs, linear, 1\.0e14 W/cm2\. No uncertainty is printed\. zhao\_2023/ker\_N2plus\_O ~~~~~~~~~~~~~~~~~~~~~~~~~ .. code-block:: text { "id": "ker_N2plus_O", "material": "N2O", "table": "text", "quantity": "kinetic_energy_release", "unit": "eV", "abscissa": "none", "use": "primary", "parameters": { "channel": "N2O+ -> N2+ + O(3P)", "kind": "asymptotic", "state": "N2O+ B 2Pi (assigned)", "wavelength_nm": 800, "pulse_fs": 35, "polarization": "linear", "intensity_w_cm2": 100000000000000.0 } } 1 inline points in the source record. p\. 3 \(TC\-971\)\: the asymptote at 6 ps of the delay\-dependent KER of the N2\+ \+ O\+ pairs \(as ker\_NOplus\_N\)\. No uncertainty is printed\. zhao\_2023/ker\_NOplus\_N\_calc ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ .. code-block:: text { "id": "ker_NOplus_N_calc", "material": "N2O", "table": "text", "quantity": "kinetic_energy_release", "unit": "eV", "abscissa": "none", "use": "check", "parameters": { "channel": "N2O+ -> NO+ + N(2D)", "kind": "calculated", "state": "N2O+ B 2Pi" } } 1 inline points in the source record. p\. 3 \(TC\-971\)\: the simulated \(Landau\-Zener surface hopping on CASSCF surfaces, fragments in their ground states\) asymptote at 6 ps for NO\+ \+ N\+, against the measured 0\.6 eV\. zhao\_2023/ker\_N2plus\_O\_calc ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ .. code-block:: text { "id": "ker_N2plus_O_calc", "material": "N2O", "table": "text", "quantity": "kinetic_energy_release", "unit": "eV", "abscissa": "none", "use": "check", "parameters": { "channel": "N2O+ -> N2+ + O(3P)", "kind": "calculated", "state": "N2O+ B 2Pi" } } 1 inline points in the source record. p\. 3 \(TC\-971\)\: the simulated asymptote at 6 ps for N2\+ \+ O\+, against the measured 0\.4 eV\. zhao\_2023/time\_NOplus\_N ~~~~~~~~~~~~~~~~~~~~~~~~~~ .. code-block:: text { "id": "time_NOplus_N", "material": "N2O", "table": "text", "quantity": "dissociation_time", "unit": "ps", "abscissa": "none", "use": "check", "parameters": { "channel": "N2O+ (B 2Pi) -> NO+ + N", "kind": "appearance time of the fragments (KER at its asymptote)", "wavelength_nm": 800, "pulse_fs": 35, "polarization": "linear", "intensity_w_cm2": 100000000000000.0 } } 1 inline points in the source record. pp\. 3\-4 \(TC\-971\)\: 'The KER reaches the dissociation energy for both channels at around 1 ps, suggesting that the ultrafast dissociation of both channels is complete within the first ps'\. A completion time read from the KER curves, 'around 1 ps', not a fitted time constant; the rise times of the channels are in the supplement \(not in the library\)\. zhao\_2023/time\_N2plus\_O ~~~~~~~~~~~~~~~~~~~~~~~~~~ .. code-block:: text { "id": "time_N2plus_O", "material": "N2O", "table": "text", "quantity": "dissociation_time", "unit": "ps", "abscissa": "none", "use": "check", "parameters": { "channel": "N2O+ (B 2Pi) -> N2+ + O", "kind": "appearance time of the fragments (KER at its asymptote)", "wavelength_nm": 800, "pulse_fs": 35, "polarization": "linear", "intensity_w_cm2": 100000000000000.0 } } 1 inline points in the source record. pp\. 3\-4 \(TC\-971\)\: as time\_NOplus\_N; the paper gives one time for both channels\. Formulas -------- No formulas are recorded. Corrections ----------- No dataset errata are recorded in this source record. Formula corrections, where recorded, appear with their formulas above. Curation notes may also discuss corrections or unresolved interpretation. Consult the :doc:`review register ` for the checks and decisions.