Zn1–xCdxS Nanoparticles with varying Cd concentration were synthesized via co-precipitation technique at 280 K. Despite the analogous size, the nanoparticles with different Cd content exhibit composition-dependent absorption resulting from the distinguished band gap. Due to size effect Zn1–xCdxS nanoparticles, self activated PL band shifted to higher energies compared to the absorption band of bulk counterpart. Origin of the PL emission bands are investigated via fluorescence lifetime measurement. Decay time constant is found in nano second regime and is attributed to the spatial confinement of photo generated electron-hole pairs.

Electron Emission from Diamondoids: A Diffusion Quantum Monte Carlo Study We present density-functional theory (DFT) and quantum Monte Carlo (QMC) calculations designed to resolve experimental and theoretical controversies over the optical properties of H-terminated C nanoparticles (diamondoids). The QMC results follow the trends of well-converged plane-wave DFT calculations for the size dependence of the optical gap, but they predict gaps that are 1-2 eV higher. They confirm that quantum confinement effects disappear in diamondoids larger than 1 nm, which have gaps below that of bulk diamond. Our QMC calculations predict a small exciton binding energy and a negative electron affinity (NEA) for diamondoids up to 1 nm, resulting from the delocalized nature of the lowest unoccupied molecular orbital. The NEA suggests a range of possible applications of diamondoids as low-voltage electron emitters. Published as: Phys. Rev. Lett. 95, 096801 (2005) DOI: 10.1103/PhysRevLett.95.096801 arXiv categories: cond-mat.mtrl-sci

Optical switching in graded plasmonic waveguides A new mechanism of longitudinal confinement of optical energy via coupled plasmon modes is proposed in chains of noble metal nanoparticles embedded in a graded dielectric medium, which is analogous to the confinement of electrons in semiconductor quantum wells. In these systems, one can control the transmission of optical energy by varying the graded refractive index of the host medium or the separation between the nanoparticles to realize the photonic analogue of electronic transistors. Possible passband tunability by nanoparticle spacing and modulation of the refractive index in the host medium have been presented explicitly and compared favorably with numerical calculations. Published as: Appl. Phys. Lett. 88, 241111 (2006) DOI: 10.1063/1.2210287 arXiv categories: cond-mat.mtrl-sci cond-mat.soft physics.comp-ph physics.optics

Abstract Gold nanoparticles (AuNPs) have emerged as promising tools in cancer theranostics, particularly in applications involving photoacoustic imaging (PAI) and photothermal therapy (PTT). The optical and thermal properties of AuNPs can be precisely tuned by adjusting their shape and size, which, in turn, influences their performance within the first (NIR‐I) and second near‐infrared (NIR‐II) bio‐windows. This study explores how variations in the morphology of AuNPs, such as nanorods and nanodumbbells, affect their longitudinal surface plasmon resonance peaks, penetration depth, heating efficiency, and photoacoustic performance. Special attention is given to the superior capabilities of PEGylated NIR‐II AuNPs in deep tissue imaging, photothermal conversion efficiency, effective tumor ablation, and biocompatibility compared to their NIR‐I counterparts. NIR‐II AuNPs also demonstrate significantly enhanced photoacoustic intensity, making them highly promising for clinical PAI. These findings underscore the potential of NIR‐II‐optimized AuNPs as potent agents for cancer theranostics, providing valuable insights into how the shape and size of AuNPs influence the aspect ratio, thereby optimizing imaging precision and treatment efficacy across the NIR‐I to NIR‐II spectrum.

The purpose of this research is to examine how the electro-optical behavior of platinum (Pt) nanoparticles prepared via the gamma radiolysis process is related to both the radiation dose and to the Pt precursor concentration. The Pt precursor used in these experiments has been radiolytically degraded using a ⁶⁰Co gamma source at dosages ranging from 80 kGy to 120 kGy. As well, varying the concentration of the Pt precursor from 5.0 × 10^-4 M to 20.0 × 10^-4 M was carried out as a systematic investigation. Spectrophotometric analysis utilizing UV-Visible spectroscopy and TEM provided the optical data and particle size information for the nanoparticles. The results indicate that increasing the radiation dosage results in smaller Pt nanoparticle sizes due to an increased rate of nucleation and that increasing the Pt precursor concentration leads to larger Pt nanoparticles due to an increase in ion recombination. Both the dose and concentration dependency of the optical absorption spectrum indicate a significant relationship between size and plasmon behavior. Also, the conduction band energy level, which was determined from the maximum of the UV-Visible absorption peak, is dependent on the particle size and shows a pronounced quantum confinement effect, with the conduction band energy increasing as the particle size decreases. Thus, these studies provide a definitive correlation of structure-property in Pt nanoparticles and confirm the capability of the gamma radiolytic synthesis process to be used for controlling the specific electronic and optical properties of Pt nanoparticles.

Abstract This article demonstrates the effect of X-ray on structure, morphology and optical properties of zinc oxide (ZnO) nano powder. The characteristics were investigated using XRD, FE-SEM, EDX and UV–vis spectroscopy. In this study, X-ray with doses equivalent to 10 (S2) and 20 Gy (S3) Gy were used to irradiate ZnO. The XRD analysis shows that the average crystallite size for non-irradiated ZnO (S1) is 49.39 nm. The crystallite size was reduced to 45.69 when irradiated at 10 Gy dose (S2) and further reduced to 45.18 nm when irradiated at 20 Gy dose. The FE-SEM analysis shows that the average maximum grain size of the non-irradiated ZnO sample (S1) is 151 nm. The average grain size was found reduced to 138 nm when irradiated at 10 Gy dose (S2) and further reduced to 115 nm when irradiated at dose equivalent to 20 Gy (S3). The FE-SEM analysis showed that the non-irradiated ZnO displayed hexagonal shape with sharp edges. On FE-SEM images, the ZnO displayed sharp edges with hexagonal shape. After irradiation, the FE-SEM images showed that the shape to be less sharp (blunt) but the hexagonal characteristic was maintained for both S2 and S3. The elemental composition of the ZnO via EDX analysis showed no effect and changes on X-ray irradiation. The UV–visible analysis showed that the energy band gap, Eg increased from 3.11 before irradiation (S1) to 3.18 (S2) and 3.197 eV (S3) after irradiation by 10 Gy and 20 Gy respectively. In summary, this study shows that X-ray irradiation

The small size of nanoparticles gives them with properties that can be very useful in oncology, particularly in imaging. Quantum dots (nanoparticles with Nanomedicine or nanotherapeutics is the medical application of nanotechnology, translating historic nanoscience insights and inventions into practical application. Nanomedicine ranges from the medical applications of nanomaterials and biological devices, to nanoelectronic biosensors, and even possible future applications of molecular nanotechnology such as biological machines. Current problems for Nanotechnology has provided the possibility of delivering drugs to specific cells using nanoparticles. This use of drug delivery systems was first proposed by Gregory Gregoriadis in 1974, who outlined liposomes as a drug delivery system for chemotherapy. The overall drug consumption and side-effects may be lowered significantly by depositing the active pharmaceutical agent in the diseased region only and in no higher dose than needed. Targeted drug delivery is intended to reduce the side effects of drugs in tandem decreases in consumption and treatment expenses. Additionally, targeted drug delivery reduces the side effects of crude or naturally occurring drugs by minimizing undesired exposure to healthy cells. Drug delivery focuses on maximizing bioavailability both at specific places in the body and over a period of time. This can potentially be achieved by molecular targeting by nanoengineered devices. A benefit of using nanoscale for medical technologies is that smaller devices are less invasive and can possibly be implanted inside the body, plus biochemical reaction times are much shorter. These devices are faster and more sensitive than typical drug delivery. The efficacy of drug delivery through nanomedicine is largely based upon: a) efficient encapsulation of the drugs, b) successful delivery of drug to the targeted region of the body, and c) successful release of the drug. Several nano-delivery drugs were on the market by 2019. Drug delivery systems, lipid- or polymer-based nanoparticles, can be designed to improve the pharmacokinetics and biodistribution of the drug. However, the pharmacokinetics and pharmacodynamics of nanomedicine is highly variable among different patients. When designed to avoid the body's defense mechanisms, nanoparticles have beneficial properties that can be used to improve drug delivery. Complex drug delivery mechanisms are being developed, including the ability to get drugs through cell membranes and into cell cytoplasm. Triggered response is one way for drug molecules to be used more efficiently. Drugs are placed in the body and only activate on encountering a particular signal. For example, a drug with poor solubility will…

fine- tuning the optical and electronic properties of this material. Additionally, the optical properties … materials or with electronic properties of nanosystems (quantum dots, quantum computers, etc.). Clearly … crystallite dimensions and size distribution, bond angle disorder, and stress, affect the Raman line shape