Adsorption Study and Detection of the High Performance Organic Pigments Quinacridone and 2,9-Dimethylquinacridone on Ag Nanoparticles By Surface-Enhanced Optical Spectroscopy

Abstract

In this work, surface-enhanced Raman scattering (SERS) and surface-enhanced fluorescence (SEF) were employed in the study of the adsorption and detection of the pigments quinacridone (QA) and 2,9dimethylquinacridone (2,9-DMQA). These pigments are of great relevance in artwork and textile, plastic, and photochemical industries due to their condition as high performance pigments since they possess a high tinting strength. Due to this fact, they have been employed at relatively low concentrations. Therefore, the analysis and detection of these pigments requires the application of a highly sensitivity technique, such as SERS and SEF. The adsorption of QA and 2,9-DMQA on silver nanoparticles was extensively studied by means of SERS at different surface coverages. This study was completed by carrying out an in depth vibrational (Raman and IR) analysis of these pigments in solid state by ab initio density functional theory (DFT) calculations. In addition, UV−vis spectroscopy was employed to investigate the aggregation undergone by both pigments in solid state and in solution. 2,9-DMQA was demonstrated to have a lower tendency toward aggregation due to the presence of methyl groups. Even so, this molecule follows a BET adsorption mechanism on the metal nanoparticles due to its high tendency toward intermolecular interaction. From the analysis of the adsorption mechanism of this molecule, the limit of detection was deduced to be ca. 55 ppb.

Spectroscopic characterization of commercial pigments for pictorial retouching

“…Other studies [3,22,23,26,27] Bristol Yellow, pale 43101 Schulte et al [23] and Ropret et al [32] Isoindoline yellow Schulte et al [23] and Ropret et al [32] Isoindoline Yellow Caggiani et al [19] Ruiz-Preciado et al [33] Jiang et al [34] 300…”

“…de Ferri et al [20] and Sze et al [21] Irgazine Scherrer et al [22] Schulte et al [23] del Puerto et al [26] 1,132, 1,204, 1,308…”

Doping graphene via organic solid-solid wetting deposition

“…Also, further analysis in this regard revealed no shift of the DMQAC-specific peaks in the spectra of both the DMQAC samples. Furthermore, worth noting here is that the spectrum of the sample 'graphene covered with a DMQAC adsorbate layer' exhibited additional peaks, which are as well related to DMQAC [56], their determined locations being as 1408 ± 1 cm -1 , peaks could not be determined in the spectrum of the sample 'graphene covered with DMQAC powder', due to the occurrence of fluorescence ( Fig. 7 (b)) [57][58].…”

The Colors of Keith Haring: A Spectroscopic Study on the Materials of the Mural Painting Tuttomondo and on Reference Contemporary Outdoor Paints

“…However, after acidic treatment and solvent rinse, more bands related to the pigment became visible (Table 2), allowing its unambiguous identification as Quinacridone Red PR122 (Figure 3). 27 The dispersive Raman spectra of the red paint (not shown) were characterized by a significant sloping fluorescence baseline, and were dominated by the bands of calcite. The peaks of the pigment were very weak, and only the most intense bands centered at 1597 cm À1 , 1568 cm À1 , and 1311 cm À1 were barely visible.…”