cvd monolayer graphene  (Eppendorf AG)

Journal: ACS Photonics

Article Title: Self-Referencing Photothermal Common-Path Interferometry to Measure Absorption of Si 3 N 4 Membranes for Laser-Light Sails

doi: 10.1021/acsphotonics.5c01886

Figure Lengend Snippet: (a) Schematic of the photothermal common-path interferometry (PCI) setup, along with (b) a visualization of the PCI signal (with AC and DC components) and phase resulting from the time delay between chopped light and detected probe intensity. (c) Transfer of a graphene monolayer onto a sample to increase optical absorption. The measurement of absorption then involves attenuating the pump until the same value of PCI signal is measured with graphene as the unattenuated measurement without graphene. In our experiments with silicon nitride membranes, the addition of graphene did not significantly alter the PCI phase, indicating that the thermal conductance of the sample was not significantly altered.

Article Snippet: To prepare the reference sample, we transferred chemical vapour deposition (CVD)-grown monolayer graphene onto Si 3 N 4 and SiN x membranes purchased from Norcada Inc. (see Supporting Information S2 for membrane geometry) and then measured the absorptivity ( A ref ) using variable-angle spectroscopic ellipsometry (see Supporting Information S3, S4, and S8 ) to be 1.5 ± 0.11% for the ∼194 nm thick Si 3 N 4 and 2.6 ± 0.16% for the ∼2-μm thick SiN x at 1064 nm.

Techniques:

Journal: ACS Photonics

Article Title: Self-Referencing Photothermal Common-Path Interferometry to Measure Absorption of Si 3 N 4 Membranes for Laser-Light Sails

doi: 10.1021/acsphotonics.5c01886

Figure Lengend Snippet: (a) Side-view schematic of the PCI setup showing translation of the sample along the z -axis, and the AC and DC components of the detected signal. The sample is translated in the z -direction to find the peak of the AC signal, which occurs when the pump waist is at the sample surface; (b) AC component of the detected probe intensity ( V AC ) for the SiN x membrane with and without graphene. The pump intensity was manually attenuated using a variable ND-filter for the sample with graphene to obtain a V AC similar V AC to that of SiN x alone (inset). Solid lines are the measured V AC , while dashed lines represent the process of increasing attenuation to achieve a similar V AC with and without graphene. Because of this manual attenuation process over many orders of magnitude of pump power, it was possible to bring the V AC of graphene-on-SiN x very close to that of SiN x , but a slight difference in V AC remained. That difference can be addressed via when calculating the absorption. (c) V AC for the Si 3 N 4 membrane and Si 3 N 4 with graphene (data set 1), similarly obtained using a variable ND-filter. Due to the low loss of Si 3 N 4 , measurements spanned two data sets, and the average (solid lines) and standard deviation (shaded areas) of five measurements taken for Si 3 N 4 and Si 3 N 4 with graphene (data set 1) are shown. Dashed lines illustrate the process of attenuation and do not represent actual measured data. (d, e) Phase between the chopped pump and detected probe intensities vs the sample position for (d) the SiN x membrane and (e) Si 3 N 4 membrane with and without graphene (data set 1).

Article Snippet: To prepare the reference sample, we transferred chemical vapour deposition (CVD)-grown monolayer graphene onto Si 3 N 4 and SiN x membranes purchased from Norcada Inc. (see Supporting Information S2 for membrane geometry) and then measured the absorptivity ( A ref ) using variable-angle spectroscopic ellipsometry (see Supporting Information S3, S4, and S8 ) to be 1.5 ± 0.11% for the ∼194 nm thick Si 3 N 4 and 2.6 ± 0.16% for the ∼2-μm thick SiN x at 1064 nm.

Techniques: Membrane, Standard Deviation

Journal: Beilstein Journal of Nanotechnology

Article Title: Impacts of annealing on structural and photophysical properties of zinc phthalocyanine adsorbed on graphene

doi: 10.3762/bjnano.17.39

Figure Lengend Snippet: a) Micro-absorption spectra of a ZnPc:TSB35-C12 self-assembled monolayer on CVD graphene before (blue), and after 30 min annealing (purple) and 3 h annealing (red) at 80 °C. Baselines corresponding to the average graphene absorption were subtracted and the curves were vertically shifted for clarity. b) Spatial variations of the corresponding transmission spectra, represented in pseudocolor, as recorded along a 230 µm line on the sample. From top to bottom: before annealing (blue), after intermediate annealing (purple), after complete annealing (red). The Q-band absorption peaks before and after annealing (676 and 711 nm, respectively) are indicated on the spectra, together with their vibronic replicas (608 and 630 nm, respectively).

Article Snippet: In summary, the substrates were either freshly cleaved HOPG (SPI supplies, grade 2) or monolayer CVD graphene transferred from its growth Cu substrate with PMMA coating (Graphenea) on a 170 μm thick transparent microscope glass cover plate.

Techniques: Transmission Assay

Journal: Beilstein Journal of Nanotechnology

Article Title: Impacts of annealing on structural and photophysical properties of zinc phthalocyanine adsorbed on graphene

doi: 10.3762/bjnano.17.39

Figure Lengend Snippet: Raman scattering microspectroscopy excited at 633 nm for a ZnPc:TSB35-C12 self-assembled monolayer on CVD graphene before (blue) and after (red) 3 h annealing at 80 °C. The Raman photon counts are acquired with the same acquisition time and excitation intensity so that the amplitudes can be compared. The main three central peaks (1543, 1472, and 1374 cm −1 ) discussed in the text are highlighted. Neat graphene response before ZnPc and TSB35-C12 deposition (grey), for reference. The standard D, 2D, and G peaks are labelled. The insert illustrates the proposed planar-square to shuttlecock transition (G: graphene substrate).

Article Snippet: In summary, the substrates were either freshly cleaved HOPG (SPI supplies, grade 2) or monolayer CVD graphene transferred from its growth Cu substrate with PMMA coating (Graphenea) on a 170 μm thick transparent microscope glass cover plate.

Techniques:

Journal: Beilstein Journal of Nanotechnology

Article Title: Impacts of annealing on structural and photophysical properties of zinc phthalocyanine adsorbed on graphene

doi: 10.3762/bjnano.17.39

Figure Lengend Snippet: Incidence-angle dependence, as measured every 5° from 0° (normal incidence, light grey) to 65° (black), of p -polarized (TM) absorption of a self-assembled monolayer of ZnPc:TSB35-C12 on CVD graphene before (a) and after (c) annealing (3 h at 80 °C); corresponding variations of ZnPc Q-band peak amplitude at maximum before (b, 676 nm) and after (d, 711 nm) annealing. Solid and dotted lines in (b, d) represent theoretical relative variations of angle-dependent absorption for a transition dipole moment oriented either in-plane or normal to the substrate plane, respectively. The corresponding orientation hypothesis and measurement geometry are also schematized. Horizontal arrows: beam propagation direction, vertical arrow: optical electric field, S: substrate plane tilted by the variable angle θ. Blue ellipsis (µ): ZnPc transition dipole moment.

Article Snippet: In summary, the substrates were either freshly cleaved HOPG (SPI supplies, grade 2) or monolayer CVD graphene transferred from its growth Cu substrate with PMMA coating (Graphenea) on a 170 μm thick transparent microscope glass cover plate.

Techniques:

Journal: Beilstein Journal of Nanotechnology

Article Title: Impacts of annealing on structural and photophysical properties of zinc phthalocyanine adsorbed on graphene

doi: 10.3762/bjnano.17.39

Figure Lengend Snippet: Left: Micro-absorption spectra of an annealed (3 h at 80 °C, red line) or not annealed (blue line) ZnPc:TSB35-C12 self-assembled monolayer on CVD graphene after its exposition to a solution of BPDI4Py. The peak at 526 nm is assigned to BPDI4Py. The curves have been vertically shifted for clarity. Right: scheme of the proposed interpretation.

Article Snippet: In summary, the substrates were either freshly cleaved HOPG (SPI supplies, grade 2) or monolayer CVD graphene transferred from its growth Cu substrate with PMMA coating (Graphenea) on a 170 μm thick transparent microscope glass cover plate.

Techniques: