Research ArticleChemistry

Binding energy of solvated electrons and retrieval of true UV photoelectron spectra of liquids

See allHide authors and affiliations

Science Advances  30 Aug 2019:
Vol. 5, no. 8, eaaw6896
DOI: 10.1126/sciadv.aaw6896
  • Fig. 1 Experimental apparatus and photoelectron spectra of esolv.

    (A) Schematic diagram for UV pump–EUV probe photoelectron spectroscopy. OPA, optical parametric amplifier. BBO, β-BaB2O4. (B) Photoelectron spectra of an aqueous 0.5 M NaI solution at −10 and 5 ps. The eBE distributions of esolv in (C) water at 5 ps, (D) methanol at 20 ps, and (E) ethanol at 200 ps measured in 0.5 M NaI solutions. HOMO, highest occupied molecular orbital.

  • Fig. 2 Electron kinetic energy distribution Gℏω(E) created in conduction band of ethanol by photoexcitation of esolv and photoelectron distribution gℏω(E) measured experimentally.

    Dashed lines are, respectively, Gℏω(E) for ℏω of (A) 5.8, (B) 5.2, (C) 4.6, and (D) 4.1 eV calculated using the eBE distribution of esolv in ethanol determined in the present study. The mean kinetic energies of Gℏω(E) are indicated. Solid lines express gℏω(E) that are the experimental data adopted from (12).

  • Fig. 3 Ultrafast UV photoelectron spectra of CTTS reaction from I to polar protic solvents.

    PKE time-energy map measured for (A) ethanol, (B) methanol, and (C) water using 226-nm pump and 260-nm probe pulses. (D to F) The eKE time-energy map retrieved from (A) to (C), respectively. (G to I) Time evolution of VBE obtained from (A) to (C) (black) and (D) to (F) (red), respectively. The time axes are in linear scale from −1 to 3 ps and in log scale from 3 to 500 ps. Broken lines indicate the boundary of the two scales.

  • Fig. 4 Time-correlation function C(t) determined from ultrafast UV photoelectron spectra of CTTS reaction from I to polar protic solvents.

    (A) ethanol, (B) methanol, and (C) water. The original (black) and retrieved (red) data points are shown. Time constants and simulated curves in solid line were obtained by the least squares fitting. In (C), an unexpected increase of C(t) by less than 0.1 is seen after 25 ps, which was excluded from the least squares fitting.

  • Fig. 5 Ultrafast UV photoelectron spectra of internal conversion of eaq.

    (A) eBE time-energy map measured for ultrafast internal conversion of eaq with the 720-nm pump and 270-nm probe pulses. (B) Retrieved eBE time-energy map. (C) Negative signals component calculated from the photoelectron spectrum separately measured and retrieved for eaq at thermal equilibrium. (D) Positive signal component of the distribution calculated from (B) and (C). (E) Signal from the ground state in (D). (F) Signal from the excited state in (D). (G) Prediction of photoelectron spectra obtained with 5-fs time resolution.

  • Fig. 6 Time-correlation function C(t) in the ground state of eaq calculated from the data shown in Fig. 5E

    Time constants and simulated curves in solid line were obtained by the least squares fitting.

Supplementary Materials

  • Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/5/8/eaaw6896/DC1

    Supplementary Text

    Section S1. EUV photoelectron spectrometer and eBE distribution of esolv in methanol at the delay time of 100 ps

    Section S2. Retrieval of eKE distribution before inelastic scattering

    Section S2.1. Energy-dependent transmission efficiency T(E) at liquid-gas interface

    Section S2.2. Influence of T(E) on estimated yield of esolv

    Section S3. Retrieval method

    Section S3.1. Basis functions

    Section S3.2. Determination of expansion coefficients

    Section S3.3. Transformation of gi(E) to Gi(E)

    Section S3.4. Compatibility of the basis functions among three solvents

    Section S3.5. Influence of the number of basis functions on spectral retrieval

    Section S4. Results of least squares fitting determining the expansion coefficients

    Section S4.1. CTTS reaction from I to ethanol, methanol, and water

    Section S4.2. Internal conversion of eaq

    Section S5. Comparison of kinetic time constants of original and retrieved spectra

    Section S5.1. Global fitting results of the spectra measured for CTTS reaction from I to ethanol, methanol, and water

    Section S6. Deconvolution of cross-correlation function from the observed time-energy map

    Fig. S1. Ultrafast EUV photoelectron spectroscopy of liquids.

    Fig. S2. Influence of T(E) on color map and yield.

    Fig. S3. An example of retrieving process.

    Fig. S4. Influence of T(E) on retrieving results.

    Fig. S5. Comparisons of PKE spectra resulting from same eKE distribution among three solvents.

    Fig. S6. Dependence of spectral retrieval on the number of basis functions.

    Fig. S7. Fitting of photoemission signal obtained for NaI ethanol solution as a function of delay time between pump (226 nm) and probe (260 nm) pulses.

    Fig. S8. Fitting of photoemission signal obtained for NaI methanol solution as a function of delay time between pump (226 nm) and probe (260 nm) pulses.

    Fig. S9. Fitting of photoemission signal obtained for aqueous NaI solution as a function of delay time between pump (226 nm) and probe (260 nm) pulses.

    Fig. S10. Fitting of photoemission signal obtained for internal conversion of eaq at 84 fs.

    Fig. S11. Fitting of photoemission signal obtained for internal conversion of eaq as a function of delay time between pump (720 nm) and probe (270 nm) pulses.

    Fig. S12. Global fit of the original and retrieved spectra of CTTS reaction from I to ethanol.

    Fig. S13. Global fit of the original and retrieved spectra of CTTS reaction from I to methanol.

    Fig. S14. Global fit of the original and retrieved spectra of CTTS reaction from I to water.

    Table S1. Basis function used in the retrieval of the spectra of CTTS reactions from I in three solvents.

    Table S2. Basis function used in the retrieval of the spectra of internal conversion of eaq.

    Table S3. Number of basis functions used for simulation shown in fig. S6 and their energy spacings.

    Table S4. Fitting parameters obtained by global fitting of the spectra of CTTS reactions from I in three solvents.

    References (3538)

  • Supplementary Materials

    This PDF file includes:

    • Supplementary Text
    • Section S1. EUV photoelectron spectrometer and eBE distribution of esolv in methanol at the delay time of 100 ps
    • Section S2. Retrieval of eKE distribution before inelastic scattering
    • Section S2.1. Energy-dependent transmission efficiency T(E) at liquid-gas interface
    • Section S2.2. Influence of T(E) on estimated yield of esolv
    • Section S3. Retrieval method
    • Section S3.1. Basis functions
    • Section S3.2. Determination of expansion coefficients
    • Section S3.3. Transformation of gi(E) to Gi(E)
    • Section S3.4. Compatibility of the basis functions among three solvents
    • Section S3.5. Influence of the number of basis functions on spectral retrieval
    • Section S4. Results of least squares fitting determining the expansion coefficients
    • Section S4.1. CTTS reaction from I to ethanol, methanol, and water
    • Section S4.2. Internal conversion of eaq
    • Section S5. Comparison of kinetic time constants of original and retrieved spectra
    • Section S5.1. Global fitting results of the spectra measured for CTTS reaction from I to ethanol, methanol, and water
    • Section S6. Deconvolution of cross-correlation function from the observed time-energy map
    • Fig. S1. Ultrafast EUV photoelectron spectroscopy of liquids.
    • Fig. S2. Influence of T(E) on color map and yield.
    • Fig. S3. An example of retrieving process.
    • Fig. S4. Influence of T(E) on retrieving results.
    • Fig. S5. Comparisons of PKE spectra resulting from same eKE distribution among three solvents.
    • Fig. S6. Dependence of spectral retrieval on the number of basis functions.
    • Fig. S7. Fitting of photoemission signal obtained for NaI ethanol solution as a function of delay time between pump (226 nm) and probe (260 nm) pulses.
    • Fig. S8. Fitting of photoemission signal obtained for NaI methanol solution as a function of delay time between pump (226 nm) and probe (260 nm) pulses.
    • Fig. S9. Fitting of photoemission signal obtained for aqueous NaI solution as a function of delay time between pump (226 nm) and probe (260 nm) pulses.
    • Fig. S10. Fitting of photoemission signal obtained for internal conversion of eaq at 84 fs.
    • Fig. S11. Fitting of photoemission signal obtained for internal conversion of eaq as a function of delay time between pump (720 nm) and probe (270 nm) pulses.
    • Fig. S12. Global fit of the original and retrieved spectra of CTTS reaction from I to ethanol.
    • Fig. S13. Global fit of the original and retrieved spectra of CTTS reaction from I to methanol.
    • Fig. S14. Global fit of the original and retrieved spectra of CTTS reaction from I to water.
    • Table S1. Basis function used in the retrieval of the spectra of CTTS reactions from I in three solvents.
    • Table S2. Basis function used in the retrieval of the spectra of internal conversion of eaq.
    • Table S3. Number of basis functions used for simulation shown in fig. S6 and their energy spacings.
    • Table S4. Fitting parameters obtained by global fitting of the spectra of CTTS reactions from I in three solvents.
    • References (3538)

    Download PDF

    Files in this Data Supplement:

Stay Connected to Science Advances

Navigate This Article