Protected ultrathin cuprous oxide film for photocatalysis: Excitation and relaxation dynamics

The main data analysis was done with Wavemetrics Igor Pro 7.08 using user-defined macros. Data files given in *.itx
format are human-readable text files that can be opened in Igor Pro. User-defined macros are available from the
authors upon reasonable request. Static spectra are measured with the proprietary "Croissant" software for the
channeltron analyzer and saved in human-readable *.plsp format, or SpecsLab Prodigy 4.60.1 for the 2D analyzer and
saved in the proprietary SPECS *.sle format or exported into *.itx format. Time-resolved spectra are measured with a
proprietary LabView program and exported in the binary HDF5 *.h5 file format.

******************************************** Fig. 1 LEED and He Ia ARPES ********************************************
LEED images taken with SBIG STF-8300 CCD Camera, the SBIG format is a 16-bit grayscale bitmap with metadata.
Fig. 1a: LEED image at 120 eV
LEED220210_120eV_Cu111_hBN_Cu2O.SBIG
Fig. 1b: LEED image at 48 eV
LEED220210_048eV_Cu111_hBN_Cu2O.SBIG

other energies (not shown in the figure): see Fig. S2/S3

Fig. 1c: He Ia spectrum second derivative as function of parallel momentum and binding energy
Spectra measured with VG ESCALAB 220 channeltron hemispherical analyzer by tilting the sample at two fixed azimuthal
angles and using a Gammadata VUV 5050 monochromated helium lamp. The azimuthal angles correspond to the M and K
directions, respectively, as determined by x-ray photoelectron diffraction of the Cu(111) surface. Measurement
parameters are given in the files.
Positive parallel momentum: M direction, VG2Z220628N015.plsp
Negative parallel momentum: K direction, VG2Z220628N016.plsp
Combined ARPES spectrum as a function of parallel momentum and binding energy: VG2Z220628N015_N016.itx
Second derivative along energy direction: VG2Z220628N015_N016d.itx; smoothed: VG2Z220628N015_N016d_smth.itx

************************************************ Fig. 2 He IIa ARPES ************************************************
All ARPES spectra measured with SPECS Phoibos 150 WAL hemispherical analyzer (2D detector) using SpecsLab Prodigy
software and non-monochromated helium lamp.

Fig. 2a: Detail of He IIa spectrum measured on h-BN/Cu(111)
Full angle-resolved spectrum (intensity as function of angular coordinate and kinetic energy), summed over all energy
channels and scans, exported from SpecsLab Prodigy as Igor Text. All measurement parameters are given in the file.
Spectrum HeIIa h-BN Cu111 20201023.itx
Spectrum scale converted into parallel momentum and binding energy: Spectrum HeIIa h-BN Cu111 20201023 k2.itx

Fig. 2b: Detail of He IIa spectrum measured on h-BN/Cu2O/Cu(111)
Full angle-resolved spectrum (intensity as function of angular coordinate and kinetic energy), summed over all energy
channels and scans, exported from SpecsLab Prodigy as Igor Text. All measurement parameters are given in the file.
Spectrum HeIIa h-BN Cu2O Cu111 20220211.itx
Spectrum scale converted into parallel momentum and binding energy: Spectrum HeIIa h-BN Cu2O Cu111 20220211 k2.itx

Fig. 2c: Spectra integrated over given parallel momentum range
Intensity as a function of binding energy
Spectrum HeIIa h-BN Cu111 20201023 k2 042_092.txt
Spectrum HeIIa h-BN Cu2O Cu111 20220211 k2 041_091.txt

************************* Fig. 3 2PPE spectra of Cu(111), h-BN/Cu(111) and h-BN/Cu2O/Cu(111) *************************
Spectra measured with SPECS Phoibos 150 WAL hemispherical analyzer (2D detector) using SpecsLab Prodigy software and
exported as Igor Text. All measurement parameters are given in the files. 3eV wavelength was 412nm, p-polarized.
A -10V bias voltage was applied to the sample.
Cu(111) 2PPE: P=1mW, Cu111 2022-04-14_20h47m45s.itx
Cu(111) 3PPE: P=3mW, Cu111 2022-04-14_21h09m29s.itx
h-BN/Cu(111) 2PPE: P=1.0mW, 0.5mm entrance slit, Cu111 hBN Spectrum3eV_2B_ppol.itx
h-BN/Cu(111) 3PPE: P=0.4mW, 3.0mm entrance slit, Cu111 hBN Spectrum3eV_4B_ppol.itx
h-BN/Cu2O/Cu(111) 2PPE: P~0.1mW, Cu111 hBN Cu2O 2022-02-11_17h07m34s.itx
h-BN/Cu2O/Cu(111) 3PPE: P~0.1mW, Cu111 hBN Cu2O 2022-02-11_16h58m49s.itx

************************************************* Fig. 4 Delay Scan *************************************************
Delay scans are recorded with proprietary LabView software and saved in binary HDF5 format as a 3D stack of
detector images (intensity as function of angular coordinate and kinetic energy) as a function of pump-probe delay.
Bias -5V, 3eV=413nm 0.3mW p-pol, 6eV=208nm 1nA p-pol, Ekin=11.9eV, Epass=20eV,
1mm slit, exposure 10x500ms, 20 scans, 10fs steps
Raw data, 256 angular pixels x 348 energy pixels x 201 delays x 20 scans:
WAL_20220215_UZH_JB_dscan_040_0to9.h5
WAL_20220215_UZH_JB_dscan_040_10to19.h5
Sum of all scans (transposed):
WAL_20220215_UZH_JB_dscan_040_sum.h5
Cropped to active detector window and applied distortion correction and correct scaling:
dscan_20220215_040_data3Dcorrected.h5
Integrated over +-10° angular window: dscan040.itx
Background averaged over delay positions 0-19 subtracted and energy and delay scales corrected:
Fig. 4a: dscan040bgi0.itx
Delay scan with 50ps range and 0.2ps steps, not shown in figure but analyzed the same way: dscan041bgi.itx

Fig. 4b: Intensity as a function of intermediate state energy
50 fs, delay positions 40-50: dscan040t0mbg.txt
1 ps, delay positions 140-150: dscan040t2mbg.txt
10 ps, delay positions 55-65 in dscan041bgi: dscan041t3mbg.txt

Fig. 4c: detector image obtained by averaging images at delay positions 40-50 and subtracting the background image,
then correcting the angular distortion by normalizing the intensity at the Fermi energy
dscan040image_diff0.itx

************************************************* Fig. 5 Fit Curves *************************************************
The Igor Pro batch fitting procedure was used with a custom fitting function to fit the delay scan dscan040bgi
binned in 0.1 eV intervals with index 0 at -0.3 eV.
The displayed curves have index 13 (1.0 eV), 6 (0.3 eV) and 4 (0.1 eV).

Binned delay scan: dscan040bgi_pix.itx
Fit parameters: dscan040bgi_fitparams.txt
Fit result: dscan040bgi_pixRateFits.itx
Fast component: dscan040bgi_FastComponent.itx
Slow component: dscan040bgi_SlowComponent.itx

******************************************* Fig. 6 Fit Results Comparison *******************************************
Relaxation times are extracted from the batch fit results of different delay scans.
3 nJ pump: dscan040bgi_fitparams.txt dscan_220215_040
20 nJ pump: dscan010_BG4_fitparams.txt dscan220703_010
(data: dscan010_BG4.itx, binned: dscan010_BG4_pix.itx, fits: dscan010_BG4_pixFit.itx)
h-BN/Cu(111): dscan033_fitparams.txt
(binned data: dscan044_hBN_side_pix1.itx, fits: dscan033_hBN_side_pixFits.itx)
Lisowski et al.: LifetimesLisowski.txt
(data from M. Lisowski, P. A. Loukakos, U. Bovensiepen, and M. Wolf, Femtosecond Dynamics and Transport of Optically
Excited Electrons in Epitaxial Cu Films on Si(111)-7 x 7, Appl. Phys. A 79, 739 (2004))
Extrapolation: fit_LifetimesLisowski.txt, using power law tau=0.054797*E^(-1.1419)

**************************************************** Fig. S1 XPS ****************************************************
Preparation 1 before oxidation:        Preparation 1 after oxidation:        Preparation 2 after oxidation:
B 1s: VG2Z220209N005.pesp        B 1s: VG2Z220210N023.pesp        B 1s: VG2Z220628N002.pesp
N 1s: VG2Z220209N006.pesp        N 1s: VG2Z220210N024.pesp        N 1s: VG2Z220628N003.pesp
C 1s: VG2Z220209N007.pesp        C 1s: VG2Z220210N025.pesp        C 1s: VG2Z220628N004.pesp
O 1s: VG2Z220209N008.pesp        O 1s: VG2Z220210N026.pesp        O 1s: VG2Z220628N005.pesp
Cu 2p:VG2Z220209N009.pesp        Cu 2p:VG2Z220210N027.pesp        Cu 2p:VG2Z220628N006.pesp

**************************************************** Fig. S2 LEED ****************************************************
  48 eV: LEED220209_048eV_Cu111_hBN.SBIG
  70 eV: LEED220209_070eV_Cu111_hBN.SBIG
100 eV: LEED220209_100eV_Cu111_hBN.SBIG
not shown in figure:
  40 eV: LEED220209_040eV_Cu111_hBN.SBIG
120 eV: LEED220209_120eV_Cu111_hBN.SBIG

**************************************************** Fig. S3 LEED ****************************************************
  40 eV: LEED220210_040eV_Cu111_hBN_Cu2O.SBIG
  48 eV: LEED220210_048eV_Cu111_hBN_Cu2O.SBIG
  70 eV: LEED220210_070eV_Cu111_hBN_Cu2O.SBIG
100 eV: LEED220210_100eV_Cu111_hBN_Cu2O.SBIG
120 eV: LEED220210_120eV_Cu111_hBN_Cu2O.SBIG
150 eV: LEED220210_150eV_Cu111_hBN_Cu2O.SBIG

**************************************************** Fig. S4 LEED ****************************************************
  40 eV: LEED220628_040eV_Cu111_hBN_Cu2O.SBIG
  48 eV: LEED220628_048eV_Cu111_hBN_Cu2O.SBIG
  70 eV: LEED220628_070eV_Cu111_hBN_Cu2O.SBIG
100 eV: LEED220628_100eV_Cu111_hBN_Cu2O.SBIG
110 eV: LEED220628_110eV_Cu111_hBN_Cu2O.SBIG
140 eV: LEED220628_140eV_Cu111_hBN_Cu2O.SBIG
180 eV: LEED220628_180eV_Cu111_hBN_Cu2O.SBIG
not shown in figure:
120 eV: LEED220628_120eV_Cu111_hBN_Cu2O.SBIG
150 eV: LEED220628_150eV_Cu111_hBN_Cu2O.SBIG

********************************************* Fig. S5 Work function maps *********************************************
Ekin=10.4eV, Epass=20eV, 6eV=208.5nm 0.2nA p-pol, 1mm slit, -5V bias, exposure 1x500ms, 0.1mm steps, 81x81 pixels
Preparation 1:
Data cube after lens correction and correct scaling: dscan_220221_003_data3Dcorrected.h5
Integrated over all angles and brought into raster format: dscan_220221_003_raster.h5
Work function map: dscan_220221_003_rasterWF.itx
Inset: Photograph of the sample after preparation 1, "Photograph hBN Cu2O Cu.png"
Preparation 2:
Data cube after lens correction and correct scaling: dscan_220704_011_data3Dcorrected.h5
Integrated over all angles: dscan_220704_011_raster.h5
Work function map: dscan_220704_011_rasterWF.itx

************************************************ Fig. S6 Delay Scans ************************************************
See description of Fig. 4 for processing details. Pump power was measured with a thermal powermeter and probe power
was measured with a Thorlabs SM05PD7A GaP-photodiode with 14.4 mA/W sensitivity at 208nm.
The thermal powermeter has an accuracy of +-0.1mW.
1.0mW pump power at 100kHz repetition rate equals 10nJ pulse energy.
1.0nA photodiode current equals approximately 70nW probe power or 0.7 pJ probe energy.

Common settings: Bias voltage -5V, exposure time 20x500ms, 20 scans, 20fs steps, entrance slit size 1mm,
Pass energy 20eV, Kinetic energy 11.9 eV, pump wavelength 413nm, pump and probe beam are p-polarized.
Differing settings are written for each dataset.

Fig. S6a: dscan_220215_040/dscan040bgi0.itx, processed raw data: dscan_220215_040_data3Dcorrected.h5
0.3mW pump, 208nm 1.0nA probe, 10fs steps, exposure 10x500ms
Fig. S6b: dscan_220217_045/dscan045bgi.itx, processed raw data: dscan_220217_045_data3Dcorrected.h5
0.3mW pump, 208nm 1.0nA probe, 10fs steps, Ekin=13.3eV, Epass=30eV, 7mm slit, 50 scans
Fig. S6c: dscan_220216_041/dscan041bgi.itx, processed raw data: dscan_220216_041_data3Dcorrected.h5
0.3mW pump, 208nm 1.0nA probe, 200fs steps, exposure 10x500ms, 10 scans

************************************************ Fig. S7 Delay Scans ************************************************
Common settings: same as in Fig. S6

Fig. S7a: dscan_220701_020/dscan020bgi0.itx, processed raw data: dscan_220701_020_data3Dcorrected.h5
0.5mW pump, 209nm 0.9nA probe, 3mm slit
Fig. S7b: dscan_220712_029/dscan029_BG.itx, processed raw data: dscan_220712_029_data3Dcorrected.h5
1.5mW pump, 209nm 1.0nA probe
Fig. S7c: dscan_220703_010/dscan010_BG4.itx, processed raw data: dscan_220703_010_data3Dcorrected.h5
2.0mW pump, 209nm 0.9nA probe
Fig. S7d: dscan_220417_033/dscan033_hBN_side0.itx, processed raw data: dscan_220417_033_data3Dcorrected.h5
1.0mW pump, 208nm 0.1nA probe, Ekin=11.8eV, 40 scans

*********************************************** Fig. S8 Beam profiles ***********************************************
8-bit CCD images were acquired with a Basler puA1280-54um CCD camera and Basler pylonViewer 5.0 acquisition software.
Sensor resolution: 1280x960, pixel size: 3.75x3.75 micrometers
3 eV image: 10 microseconds exposure time, Spot3eV 10us 20mm.bmp
6 eV image: 100 milliseconds exposure time, Spot6eV 100ms 20mm.bmp