Optical Properties of Free and Si(001)‐Adsorbed Pyrimidinic Nucleobases

Abstract

In this work, we predict and analyze the optical spectra of pyrimidinic uracil‐like nucleobases thymine (THY), uracil (URA), and 5‐fluorouracil (5‐FU) and their reflection anisotropy spectra (RAS) upon adsorption on the silicon (001) surface. First‐principles results based on plane‐wave density functional theory show chemically sensitive features in gas phase optical absorption spectra that redshift/blueshift according to the orbitals involved in the corresponding transition. In the RAS, a characteristic lineshape is found, typical of the energetically favored “dimer bridge” configuration, and remarkably similar for all the investigated Si(001):X systems (X = THY, URA, 5‐FU). We show that molecular tilting and breaking of the glide plane symmetry have a negligible effect on the optical spectra, despite their influence on the surface bandstructure. Contrarily to gas phase spectra, chemically sensitive RAS features only appear above 4.5 eV, and can be recognized as molecular contributions consistent with gas phase optical absorption results whereas substrate effects dominate at lower energies.

Eumelanin Adsorption on Silicon: Optical Properties of Si(001)-Adsorbed Eumelanin Tetrameric Protomolecules

“…First principles calculations on organically functionalized surfaces are able to yield valuable highlights in this respect (e.g. 14,15 ), also in cases where the experimental approach cannot reach a sufficiently detailed information, being therefore a powerful and fundamental tool in this field.…”

“…Clearly, a theoretical understanding of the effects of eumelanin on the optical properties of the substrate, in addition to the above-mentioned issues, is of paramount importance to control and optimize the behavior of these composite materials in terms of both stability and photovoltaic properties. First-principles calculations on organically functionalized surfaces are able to yield valuable highlights in this respect (e.g., refs and ), also in cases where the experimental approach cannot reach a sufficiently detailed information, being therefore a powerful and fundamental tool in this field.…”

Optical properties of nanostructured antiviral and anticancer drugs

“…Take in consideration that the removal of H atoms in the adsorption of molecules at solid surfaces has been demonstrated in different cases. [80][81][82][83] It is worth mentioning that the systems C 23 B-T705, CB 11 N 12 -T705, C 24 -5FU and B 12 N 12 -5FU (respectively shown in Fig. 2c, d, g and h), show states with different multiplicity (and free radical character) due to the presence of unpaired electrons.…”

“…Take in consideration that the removal of H atoms in the adsorption of molecules at solid surfaces has been demonstrated in different cases. 80–83…”

Electronic and Optical Properties of Alkaline Earth Metal Fluoride Crystals with the Inclusion of Many-Body Effects: A Comparative Study on Rutile MgF2 and Cubic SrF2

“…Another relevant research issue to be considered is the use of ultraviolet radiation (UV) for biological, pharmacological, and medical applications, e.g., the radiation disinfection schemes in relation to the outbreaks caused by SARS-CoV-1 and SARS-CoV-2 viruses [17]. For this kind of radiation, the use of specific tools and instruments, e.g., mirrors, cuvettes, test tubes, bulbs, container tubes, separation, and cladding surfaces made by materials specific for the UV is requested in relation to the radiation disinfection-antimicrobial/antiviral issues [18][19][20][21][22]. As a consequence, there has been a boost in the research on transparent materials that could be produced, controlled, and used in specific UV radiation disinfection devices.…”