DOI: 10.20350/digitalcsic/13919
title: Dataset for the paper “Oujja, M., Agua, F., Sanz, M., Morales-Martín, D., García-Heras, M., Villegas M.A., Castillejo, M. 2021. Multiphoton Excitation Fluorescence Microscopy and Spectroscopic Multianalytical Approach for Characterization of Historical Glass Grisailles. Talanta 230, 122314”

description: Laser-induced Breakdown Spectrocopy (LIBS) analyses were performed using laser excitation at 266 nm (Nd:YAG laser, 6 ns pulses, 10 Hz repetition rate; Quantel Brilliant) and a 0.30 m spectrograph with a 1200 grooves/mm grating (TMc300 Bentham) coupled to an intensified charged coupled detector (ICCD, 2151 Andor Technologies). The laser beam was conducted to the surface of the base glass and grisaille paint layers by using mirrors at an angle of incidence of 45º and a focal length of 10 cm. The fluence was of 6.6 J cm− 2 (2 mJ laser pulse energy and 200 μm laser spot diameter). LIBS spectra were recorded with a gate delay and width of 100 ns and 3 μs, respectively, a resolution of 0.025 nm and 10 accumulations. 2 files per sample of the LIBS elemental composition of glass without grisaille (body surface) and the grisaille itself are included. Each file is composed of 12 columns (6 consecutive spectra between 292-605 nm). A 300 nm cut-off filter was placed in front of the input window of the spectrograph to reduce scattered laser light from the sample surface and avoid second order diffraction in 6 of the five spectrum. For the Laser-induced Fluorescence (LIF) analyses, the same equipment described above was used. However, time gate was operated with a zero-time delay, the grating was 300 lines/mm and the number of accumulations of 25. The sample was illuminated through a pinhole, to select the central part of the unfocused laser beam, giving rise to a spot on the sample of elliptical shape with dimensions of 1 mm × 2 mm at an incidence angle of 45º. The fluence was 6 × 10− 3 J cm− 2. 2 files per sample of the analysis of fluorescent species of each glass without grisaille (body surface) and the grisaille itself are included. Each file is composed of 4 columns (2 consecutive and partially overlapped spectra between 275-700 nm). A cut-off filter at 300 nm was also used as for the LIBS measurements. A home-made nonlinear optical microscope (NLOM) was used for Multi-Photon Excitation Fluorescence (MPEF) measurements. MPEF signals originated from the focal volume in the sample plane of a mode-locked Ti:Sapphire femtosecond laser. The laser emits at 800 nm, with an average power of 680 mW, delivering 70 fs pulses at a repetition rate of 80 MHz. A variable neutral density filter (NDC-50C-2M, Thorlabs) controled the laser power reaching the sample that was in the range of 6–9 mW. The laser beam was modulated using a chopper at a frequency of 130 Hz and conducted to the sample through the aperture of a microscope objective lens (M Plan Apo HL 50X, Mitutoyo, NA 0.42) by using a dichroic beam splitter (FF750-SDi02-25x36, Semrock) with a high reflection at 800 nm. The focal plane of the laser was selected with motorized translation XYZ stages (Standa 8MVT100-25-1 for XY and Standa 8MTF for Z). The lateral and axial resolutions achieved are of 1 and 2 μm, respectively. A LabVIEW interface controlled both scanning and data acquisition procedures. MPEF signals were collected in the backward direction through the microscope objective lens and a beam splitter (70/30) and measured using a photomultiplier tube (9783B, ET Enterprises) connected to a lock-in amplifier (SR810 DSP, Stanford Research Systems) to ensure high amplification and signal-to-noise ratio. To cut off the reflected excitation laser light, a short pass filter (335–610 nm, Thorlabs FGB37S) was placed at the entrance of the photomultiplier. The remaining 30% of the MPEF signal was sent to a CCD camera (Thorlabs DCC1645C) for online visualization of the sample surface. The photon dose applied to the surface of the sample was 80 × 106 pulses/point. Each MPEF profile resulted from 300 measurements during the whole Z-scan using a step of 1 μm/per second, then the time required to complete each MPEF profile corresponds to 5 min. For NLOM, 2 files per sample of depth scans of the MPEF signals with the lowest (l) and highest (h) grisaille thickness are included. Each file is composed of 5 columns: 3 are MPEF signal (normalized and smooth) and 2 Lorentzian fit. (The thicknesses of the grisaille paints is calculated by the FWHM values of the fits after refractive index corrections). In-depth cross section imaging of carbon coated glasses decorated with grisaille paint was carried out by Field Emission Scanning Electron Microscope (FESEM) with a Hitachi S-4800 cold cathode equipment, working with acceleration voltage of 15 kV. An Oxford X-Max of 20 mm2 system coupled to the electron microscope with resolution of 125 eV (Mg Kα) was used for Energy Dispersive X-Ray Spectroscopy (EDS) microanalyses. For the determination of the thickness of the grisaille paint, 4 cross section images, one for each glass were taken. The two distinctive zones 1 (glass) and 2 (grisaille on top) were the ones analysed by EDS and as a result 4 files (one per sample) with microanalyses of both areas are listed. Furthermore 4 conventional images of the four glass samples are included. Images taken via FESEM and conventional camera are presented in JPG. All spectra are presented in Excel format (2016), in a single page. Data life: 2021- (unlimited validity)
description: This is the experimental dataset used in the paper Talanta, 230: 122314 (2021) (http://hdl.handle.net/10261/244443) in which the thickness and composition of grisaille paints in four Spanish historical stained glasses, named Balmaseda (A; 19th century), Girona (B; 18th century), Leon (C; 13th century) and Goyeneche (D; early 20th century) after their place of origin, have been determined. The samples are glass fragments without value for their replacement available from previous conservation works made by some of the authors. This data set includes the results of the chemical and physical characterization of grisaille with a set of optical and spectroscopic techniques, including non-invasive techniques such as the emerging Nonlinear Optical Microscopy (NLOM) in the modality of Multi-Photon Excitation Fluorescence (MPEF). This allows determining the thicknesses values of the historical grisaille paint layers on the basis of their intrinsic fluorescence without photochemical and physical damage. The results obtained (FWHM values of depth scan after refractive index correction) show significant consistency and agreement with those obtained from traditional Field Emission Scanning Electron Microscope (FESEM) in which mean thickness varies between 26-78 µm. Scanning Electron Microscope coupled with Energy Dispersive X-Ray Spectroscopy (FESEM-EDS) and Laser Induced Breakdown Spectrosocopy (LIBS) show the elemental composition of both the body glass and the grisaille paint in the 4 samples according to the respective emission lines of the main and minor components. And finally, Laser Induced Fluorescence (LIF) provides complementary information (fluorescence species).
description: 1.1. LIBS_A-glass.-- 1.2. LIBS_A-grisaille.-- 1.3. LIBS_B-glass.-- 1.4. LIBS_ B-grisaille.-- 1.5. LIBS_C-glass.-- 1.6. LIBS_C-grisaille.-- 1.7. LIBS_D-glass.-- 1.8. LIBS_D_grisaille.-- 1.9. LIF_A-glass.-- 1.10. LIF_A-grisaille.-- 1.11. LIF_B-glass.-- 1.12. LIF_B-grisaille.-- 1.13. LIF_C-glass.-- 1.14. LIF_C-grisaille.-- 1.15. LIF_D-glass.-- 1.16. LIF_D-grisaille.-- 1.17. NLOM_A-grisaille_l.-- 1.18. NLOM_A-grisaille_h.-- 1.19. NLOM_B-grisaille_l.-- 1.20. NLOM_B-grisaille_h.-- 1.21. NLOM_C-grisaille_l.-- 1.22. NLOM_C-grisaille_h.-- 1.23. NLOM_D-grisaille_l.-- 1.24. NLOM_D-grisaille_h.-- 1.25. EDS_A-grisaille.-- 1.26. EDS_B-grisaille.-- 1.27. EDS_C-grisaille.-- 1.28. EDS_D-grisaille.-- 1.29. FESEM_A-grisaille.-- 1.30. FESEM_B-grisaille.-- 1.31. FESEM_C-grisaille.-- 1.32. FESEM_D-grisaille.-- 1.33. A-glass_grisaille.-- 1.34. B-glass_grisaille.-- 1.35. C-glass_grisaille.-- 1.36. D-glass_grisaille.