Thioglycolic acid

About: Thioglycolic acid is a research topic. Over the lifetime, 1231 publications have been published within this topic receiving 17883 citations. The topic is also known as: acetyl mercaptan & mercaptoacetic acid.

Strongly Photoluminescent CdTe Nanocrystals by Proper Surface Modification

Abstract: CdTe nanoclusters were prepared in aqueous solution by the reaction between Cd2+ and NaHTe in the presence of thioglycolic acid. Under reflux, the clusters start to crystallize and show a narrow band emission. The photoluminescence efficiency of CdTe nanocrystals strongly depends on the pH value of the colloidal solution. The maximum quantum yield at room temperature is approximately 18% when the pH value of the CdTe solution is brought to 4.5 by using thioglycolic acid. The optical spectroscopy studies imply that the pH-dependent behavior of the CdTe nanocrystals' fluorescence is caused by structural changes on the surface rather than the size of the nanocrystals. Systematic absorption and fluorescence studies on dialyzed samples suggest that in the acidic range a shell of cadmium thiol complexes is formed around the CdTe core. Thus, the fluorescence quantum yield is enhanced dramatically when the solution is made acidic. In contrast, such a shell can also be produced in the alkaline range, but only afte...

The Influence of Carboxyl Groups on the Photoluminescence of Mercaptocarboxylic Acid-Stabilized CdTe Nanoparticles

Abstract: The CdTe nanoparticles were prepared in aqueous solution using different mercaptocarboxylic acids such as 3-mercaptopropionic acid (MPA) and thioglycolic acid (TGA) as stabilizing agents following the synthetic route described in ref 9. The pH-dependent photoluminescence (PL) of MPA- and TGA-stabilized CdTe nanoparticles was systematically investigated before and after addition of poly(acrylic acid) (PAA) into the CdTe solutions. Experimental results reveal that lowering the pH can increase the PL efficiency of both MPA- and TGA-stabilized CdTe. Moreover, the PL of the CdTe can further be increased in the presence of PAA in low pH range. X-ray photoelectron spectroscopy (XPS) was employed to investigate the interaction between the carboxyl groups from PAA and CdTe nanoparticles which were assembled in polymer matrix by a layer-by-layer self-assembly method to exclude interference from other species in CdTe solutions. XPS results demonstrate that the S/Te ratio of CdTe particles decreases after the additio...

Synthesis and Characterization of a Size Series of Extremely Small Thiol-Stabilized CdSe Nanocrystals

Abstract: As an expansion to the wet chemical route for the preparation of quantum-sized II−VI semiconductor materials, a series of thiol-capped crystalline CdSe nanoparticles has been synthesized in aqueous solution using mercapto- alcohols (2-mercaptoethanol, 1-thioglycerol), and mercapto acids (thioglycolic acid, thiolactic acid) as stabilizers The smaller (app 14−22 nm diameter) CdSe particles were obtained using thioalcohols as capping agents; the use of thioacids as stabilizers produced larger (21−32 nm diameter) CdSe particles CdSe nanoparticles were separated from the crude solutions as redissolvable powder samples with narrow size distributions using a size-selective fractionation and have been characterized by UV−vis absorption and photoluminescence spectroscopy, X-ray diffraction, high-resolution transmission electron microscopy, and energy-dispersive X-ray analysis A calculation of the HOMO−LUMO gap of CdSe particles as a function of their size has been done using an extended effective mass appr