Md Wahadoszamen

• PhD
• Professor at University of Dhaka, Bangladesh

The techniques we describe herein are straightforward yet incredibly efficient in providing a favorable environment for two-dimensional (2D) zinc oxide nanoflakes (ZnONFs) to greatly increase the intensity of surface-enhanced Raman scattering (SERS) and produce significant photoinduced-enhanced Raman scattering (PIERS). Rhodamine 6G (R6G) was used...

Generative neural network models produce multiple designs tailored to a specific desired property, which offers researchers greater flexibility in selecting designs that balances accuracy and convenience.

In this study, we conducted a comprehensive investigation on a series of gold (core) @ silver (shell) bimetallic nanoparticles (Au@Ag BNPs) through surface-enhanced Raman spectroscopy (SERS) and the Z-scan technique to characterize and compare them in terms of optical properties. Four batches of Au@Ag BNPs with variable shell thickness were prepare...

In this study, we investigated the size-and shape-dependent optical nonlinearity of silver nanoparticles (AgNPs), and their modulation upon mixing with 2D ZnO nanoflakes (ZnONFs) using a Z-scan technique powered by a continuous-wave 514.5 nm Ar-ion laser source. We prepared three batches of AgNPs with varying average particle sizes of 36 nm, 64 nm,...

In this work, we applied Stark fluorescence spectroscopy to an iron-stressed cyanobacterial membrane to reveal key insights about the electronic structures and excited state dynamics of the two important pigment-protein complexes, IsiA and PSII, both of which prevail simultaneously within the membrane during iron deficiency and whose fluorescence s...

Rice straw is a waste product from rice manufacturing that contains cellulose (32–47%), hemicellulose (19-27%), lignin (5–24%), and ash (13–20%). The ash form consists of a large percentage of silicon dioxide (SiO2) with widespread use in the industrial field. The extraction of silicon dioxide has been conducted using the sol-gel and ashing method...

Laser-induced breakdown spectroscopy (LIBS) has emerged as a promising technique for both quantitative and qualitative analysis of elements in a wide variety of samples. However, conventional LIBS suffers from a high limit of detection (LoD) compared with other analytical techniques. This review briefly discusses several methods that demonstrate th...

We report herein an economically cheap and functionally stable surface-enhanced Raman scattering (SERS) protocol of two photoactive pigments Rhodamine 6G (R6G) and Kiton Red (KR), implemented in thin films of silver (Ag) and gold (Au) nanoparticles (AgNPs and AuNPs). Both commercially available and chemically synthesized nanoparticles were used. Th...

Reported herein is a Stark fluorescence (SF) spectroscopy study performed on photosystem II core antenna complexes CP43 and CP47 in their native and aggregated states. The systematic mathematical modeling of the SF spectra with the aid of conventional Liptay formalism revealed that induction of aggregation in both the core antenna complexes via det...

Two types of adsorbents, zinc oxide (ZnO) and zeolite, have been used to probe the lowest detectable limit of lead (Pb) dissolved in water. To achieve the goal, water-soluble Pb complexes were produced by dissolving in water or titrating with HNO3 acid with different concentrations of four different compounds of Pb. The dissolved Pb complexes were...

Because of their peculiar but intriguing photophysical properties, peridinin–chlorophyll–protein complexes (PCPs), the peripheral light-harvesting antenna complexes of photosynthetic dinoflagellates have been unique targets of multidimensional theoretical and experimental investigations over the last few decades. The major light-harvesting chloroph...

Phycobilisomes (PBs) absorb light and supply downstream photosynthetic processes with excitation energy in many cyanobacteria and algae. In response to a sudden increase in light intensity, excess excitation energy is photoprotectively dissipated in PBs by means of the orange carotenoid protein (OCP)-related mechanism or via a light-activated intri...

In this work, Laser Induced Breakdown Spectroscopy (LIBS) has been used for investigating the presence of heavy mineral garnet (X3Y2(SiO4)3, where the X represent either of Ca 2+ , Mg 2+ , Fe 2+ , Mn 2+ and the Y site contain either of Fe 3+ , Cr 2+ , Al 3+) in beach sand samples collected from Sitakunda, Bangladesh. To achieve the goal, in the fir...

Molecules that undergo reverse intersystem-crossing (RISC) which enables thermally-activated delayed fluorescence (TADF) represent an important advance in the development of organic-based light emitting diodes (OLEDs). The current study focuses on two blue-emitting RISC molecules employing carbazole as the donor and benzothiazole or benzoxazole der...

Solar energy captured by pigments embedded in light-harvesting complexes can be either transferred to neighboring pigments, dissipated or emitted as fluorescence. Only when it reaches a reaction center the excitation energy is stabilized in the form of a charge separation and converted into chemical energy. Well directed and regulated energy transf...

Aggregation induced conformational change of light harvesting antenna complexes is believed to constitute one of the pathways through which photosynthetic organisms can safely dissipate the surplus of energy while exposed to saturating light. In this study, Stark fluorescence (SF) spectroscopy is applied to minor antenna complexes (CP24, CP26 and C...

Lhca4 is one of the peripheral antennae of higher plant photosystem I and it is characterized by the presence of chlorophyll a with absorption and emission bands around 30 nm red-shifted compared to those of the other chlorophylls associated with plant complexes. In this work we have investigated the origin of this red shift by using the recent str...

A dispersive Raman spectrometer was used with three different excitation sources (Argon-ion, He-Ne, and Diode lasers operating at 514.5 nm, 633 nm, and 782 nm, resp.). The system was employed to a variety of Raman active compounds. Many of the compounds exhibit very strong fluorescence while being excited with a laser emitting at UV-VIS region, her...

When cyanobacteria are grown under iron-limited or other oxidative stress conditions the iron stress inducible pigment-protein IsiA is synthesized in variable amounts. IsiA forms aggregates inside the photosynthetic membrane that strongly dissipate chlorophyll excited state energy. In this paper we applied Stark fluorescence (SF) spectroscopy at 77...

Understanding how specific protein environments affect the mechanisms of non-radiative energy dissipation within densely assembled chlorophylls in photosynthetic protein complexes is of great interest to the construction of bioinspired solar energy conversion devices. Mixing of charge-transfer and excitonic states in excitonically interacting chlor...

A dispersive Raman spectrometer was used with three different excitation sources (Argon-ion, He-Ne, and Diode lasers operating at 514.5 nm, 633 nm, and 782 nm, resp.). The system was employed to a variety of Raman active compounds. Many of the compounds exhibit very strong fluorescence while being excited with a laser emitting at UV-VIS region, her...

A dispersive Raman spectrometer was used with three different excitation sources (Argon-ion, He-Ne, and Diode lasers operating at 514.5 nm, 633 nm, and 782 nm, resp.). The system was employed to a variety of Raman active compounds. Many of the compounds exhibit very strong fluorescence while being excited with a laser emitting at UV-VIS region, her...

Diatoms are characterized by very efficient photoprotective mechanisms where the excess energy is dissipated as heat in the main antenna system constituted by fucoxanthin-chlorophyll (Chl) protein complexes (FCPs). We performed Stark fluorescence spectroscopy on FCPs in their light-harvesting and energy dissipating states. Our results show that two...

In order to cope with the deleterious effects of excess light, photosynthetic organisms have developed remarkable strategies where the excess energy is dissipated as heat by the antenna system. In higher plants one main player in the process is the major light harvesting antenna of Photosystem II (PSII), LHCII. In this paper we applied Stark fluore...

Silver nanoparticles have been produced by laser ablation of silver metal in nanopure water without any chemical additives. It has been observed that laser power has a control over the size of the nanoparticles. Increasing laser power shows a clear blue shift in the absorption peak of fabricated nanoparticles indicating that the average size of the...

Laser-induced breakdown spectroscopic technique was used to study the elemental profile of beach sand samples of Bangladesh. Apart from Silicon, which is the main elemental constituent of sand, the presence of Li, Na, Mg, Al, Cl, K, Ca, Ti, Cr, Mn, Fe, Zr, Sr, Ba, Te and Zn was identified in the beach sand samples. In addition to the qualitative an...

Using the technique of Laser Induced Breakdown Spectroscopy (LIBS), which uses a pulsed laser to create plasma and advanced spectroscopic techniques, we analyzed the contents of surface water (river water) around the city of Dhaka. Several elements such as Li, C, Na, Mg, Al, K, Ca, Ti, Mn, Fe, Sr were identified in the water samples collected in ad...

Using the technique of Laser Induced Breakdown Spectroscopy, the chromium content of river bed sediment of the Buriganga River is determined at various locations. Hazardous element, chromium is found in addition to other elements such as calcium, magnesium, titanium, sodium etc. The source of this chromium is most likely to be the effluent discharg...

Silver nanoparticles have been produced by laser ablation of silver metal in nanopure water without any chemical additives. It has been observed that laser power has a control over the size of the nanoparticles. Increasing laser power shows a clear blue shift in the absorption peak of fabricated nanoparticles indicating that the average size of the...

Electroabsorption spectra of electron donating butyloxy- (OBu) or electron withdrawing butylsulfonyl (SO(2)Bu)-substituted tribenzotetraazachlorin (TBTAC)-C(60) conjugates (1 and 2, respectively) have demonstrated that significant change of the molecular polarizability is associated with the photoexcitation of 1 in the lower energy region, while th...

We constructed a laser Raman system using a commercially available infrared diode laser. The diode laser is used without any temperature controller in a stabilized power supply. Good quality Raman spectra of sufficient wavelength resolution were obtained for a variety of chemicals and products, including solid samples. Raman spectra of several edib...

Porphyrin-stilbene-porphyrin triad (mZnPst) where a central cis-stilbene unit is connected to zinc-tetraphenylporphyrin (ZnTPP) was synthesized and its binding ability with a selected guest ligand DABCO was investigated. The association constant was evaluated to be 2.47 x 10(8) M(-1), from the iterative least squares fitting to a 1 : 1 binding mode...

External electric field effects on absorption, fluorescence, and phosphorescence spectra of a series of unsubstituted diphenylpolyynes have been examined in a PMMA film. The analysis of the electroabsorption spectra indicates that the shorter diphenylpolyynes exhibit only the change in molecular polarizability, whereas the longer ones exhibit the c...

Photochemical properties of trans-3,3',5,5'-tetramethoxystilbene (TMST) have been studied in various polar solvents. The Stokes shift of trans-TMST was found to be increased with increasing solvent polarity. The fluorescence lifetime of trans-TMST experienced a large solvent effect changing from 2.3 ns in cyclohexane to 16.6 ns in acetonitrile. The...

Electroabsorption and electrofluorescence spectra of a fullerene derivative, C60(C18)2, and its mixture with zinc-tetraphenylporphyrin (ZnTPP) have been measured by using electric field modulation spectroscopy. The change in dipole moment is significant in the electroabsorption spectra both of C60(C18)2 and of a complex composed of C60(C18)2 and Zn...

Electroabsorption spectra of a mixture of tetraphenylporphyrin (TPP) and fullerene (C60) doped in a polymer film have been measured for both free-base porphyrin and its zinc analog with different concentrations of C60. The absorption band whose peak is located in a wavelength region longer than the peak of the Soret band of TPP appears, as the conc...

In a mixture of tetraphenylporphyrin (TPP) and fullerene (C60) doped in a PMMA film, fluorescence of TPP is enhanced and de‐enhanced by an electric field in zinc and free‐base compounds, respectively, indicating that the electron transfer from the excited state of TPP to C60 is decelerated in zinc compounds and accelerated in free‐base compounds by...

External electric field effects on state energy and photoexcitation dynamics have been examined for para-substituted and unsubstituted all-trans-diphenylpolyenes doped in a film, based on the steady-state and picosecond time-resolved measurements of the field effects on absorption and fluorescence. The substitution dependence of the electroabsorpti...

Effect of the external electric field on photoisomerization dynamics of diphenylpolyenes doped in a PMMA polymer film has been examined by using electromodulation spectroscopy in absorption and emission. A significant decrease in fluorescence intensity is found in the presence of an external electric field, suggesting that trans-to-cis isomerizatio...

We describe the construction and operation of a simple electronic speckle pattern interferometer which is sensitive to in-plane motions and rotations. The interferometer is extremely simple and easy to use. It uses a commercial digital still camera for image acquisition, and a personal computer for image storage and analysis. The interferometer was...