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Roy, Madhusudan,Alauddin, Mohammad,Song, Jae Kyu,Park, Seung Min Elsevier 2018 Spectrochimica acta. Part A, Molecular and biomole Vol.204 No.-
<P><B>Abstract</B></P> <P>Molecular structures of aniline(pyrrole)<SUP>+</SUP>, aniline(ethanol)<SUP>+</SUP>, and aniline(benzene)<SUP>+</SUP> produced via resonance two-photon ionization at 266 nm were analyzed by infrared predissociation spectroscopy coupled with tandem mass spectrometry. Structural optimization and frequency calculation using density functional theory were carried out to suggest the most probable isomers which are in good agreement with the observed infrared absorption spectra. Intermolecular bonds in the cluster ions were formed such that the electronegative oxygen atom of the solvent molecule or the pi electron of the aromatic ring forms a hydrogen bonding to NH of aniline.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Structures of heterodimer cluster ions including aniline are analyzed by IR spectroscopy and DFT calculation. </LI> <LI> Cluster ions are stabilized by formation of hydrogen bonds </LI> <LI> Hydrogen bonds are formed between NH of aniline and oxygen or π electron of solvent molecule. </LI> </UL> </P> <P><B>Graphical Abstract</B></P> <P>[DISPLAY OMISSION]</P>
Roy, Madhusudan,Kim, Kuk Ki,Alauddin, Md.,Song, Jae Kyu,Park, Seung Min Elsevier 2015 INTERNATIONAL JOURNAL OF MASS SPECTROMETRY Vol.379 No.-
<P><B>Abstract</B></P> <P>Vibrational predissociation spectra of aniline(pyrrole)(water)<SUB>2</SUB> <SUP>+</SUP> and aniline(pyrrole)(water)<SUB>3</SUB> <SUP>+</SUP> clusters were taken at 2700–4000cm<SUP>−1</SUP> to verify their most stable structures. One NH of aniline was bonded to the π electron of pyrrole while the other NH was bonded to water. Pyrrole molecule was arranged in such a way that NH of pyrrole formed another hydrogen bond with a water molecule nearby. Water molecule was more easily ejected than pyrrole for both AnPyW<SUB>2</SUB> <SUP>+</SUP> and AnPyW<SUB>3</SUB> <SUP>+</SUP> although pyrrole had smaller binding energy than water.</P> <P><B>Highlights</B></P> <P> <UL> <LI> IR predissociation spectra of aniline(pyrrole)(water)<SUB>2</SUB> <SUP>+</SUP> and aniline(pyrrole)(water)<SUB>3</SUB> <SUP>+</SUP> were obtained. </LI> <LI> The most stable cluster structures were suggested along with DFT calculations. </LI> <LI> Water molecule was dominantly ejected by IR absorption. </LI> </UL> </P>
Alauddin Mohammad,Roy Madhusudan,Song Jae Kyu,Park Seung Min 대한화학회 2022 Bulletin of the Korean Chemical Society Vol.43 No.7
We have studied H-bonded structural rearrangement in the S0, S1, and D0 states of neutral and cationic aniline+(H2O)n (n = 0–12) clusters by adopting density functional (DFT) and time-dependent DFT (TD-DFT) theory. DFT-calculated structural rearrangement energies (SRE) increased sharply for n = 1, 2, remained nearly the same until n = 9, and increased again from n = 10 to larger clusters. This indicates that the intramolecular vibrational modes play a central role in the rearrangement energy. On the other hand, DFT-calculated thermochemical data confirmed that there is no significant change in enthalpy (H), Gibb’s free energy (G), and entropy (S) for neutral and ionized clusters. The maximum UV absorption wavelength, λmax red-shifted gradually with the increase of cluster size with respect to aniline as the hydration reduces the excitation energies. On the other hand, there was no significant change in the highest occupied molecular orbital (HOMO)-lowest unoccupied molecular orbital (LUMO) energy gap.
Structure of Mono-Hydrated Aniline Dimer Cation
Mohammad Alauddin,Madhusudan Roy,Sang Hwan Nam,Jae Kyu Song,Seung Min Park 대한화학회 2021 Bulletin of the Korean Chemical Society Vol.42 No.2
Photodissociation spectroscopy of mono-hydrated aniline dimer (An2W+) cation was performed to determine its most stable structure and the charge resonance (CR) interaction therein. In its photodissociation action spectrum, two local excitation (LE) bands at ?1.9?eV (656?nm) and?>3.0?eV (<420?nm), previously assigned to 2?? 1 and 1?? 1 transition, respectively, for aniline dimer (An2+), were also observed for An2W+. On the other hand, the absorption band at ?1.12?eV (1110?nm) from the CR interaction reported for An2+ disappeared in case of An2W+. Based on this infrared photodissociation action spectra supported by quantum chemical calculations, we suggest that the most stable structure of An2W+ maintains the stacked structure of An2+ but H2O molecule connected to the amino group of aniline molecule via hydrogen bonding plays a role to suppress the CR interaction.
Aggregation of Laser-Generated Gold Nanoparticles Mediated by Formalin
Md. Alauddin,Kuk Ki Kim,Madhusudan Roy,송재규,김명수,박승민 대한화학회 2013 Bulletin of the Korean Chemical Society Vol.34 No.1
We have investigated the effects of formalin on the assembly of colloidal gold nanoparticles (AuNPs) prepared by laser ablation of a solid gold target in deionized water. Upon addition of formalin, the surface plasmon resonance (SPR) band at 519 nm for pure AuNPs decreases and shifts to red while a new broad SPR band appears at ~700 nm. The red-shift is prominent with increase in the incubation time. The average size of the initial AuNPs is around 12 nm but it increases to 23 nm after addition of formalin. It turns out that formalin acts as a cationic surfactant for AuNPs with negative surface charge in the colloidal solutions. Furthermore, through analysis of the Raman spectrum of formalin and the density functional theory calculations, we confirm that methanediol is the main species in formalin which is in charge of the aggregation of AuNPs.
Park, Jin Jae,Kim, Kuk Ki,Roy, Madhusudan,Song, Jae Kyu,Park, Seung Min Korean Society of Photoscience 2015 Rapid communication in photoscience Vol.4 No.3
$SnO_2$ thin films were deposited on fused silica substrate by pulsed laser deposition under transverse magnetic field. We have explored the effects of magnetic field and ablation laser wavelength on the optical properties of laser-induced plasma plume and structural characteristics of the deposited $SnO_2$ films. Optical emission from the plume was monitored using an optical fiber to examine the influence of magnetic field on the population of the excited neutral and ionic species and their decay with times after laser ablation. Also, we employed photoluminescence, x-ray diffraction, and UV-Vis absorption to characterize $SnO_2$ films.
Aggregation of Laser-Generated Gold Nanoparticles Mediated by Formalin
Alauddin, Md.,Kim, Kuk Ki,Roy, Madhusudan,Song, Jae Kyu,Kim, Myung Soo,Park, Seung Min Korean Chemical Society 2013 Bulletin of the Korean Chemical Society Vol.34 No.1
We have investigated the effects of formalin on the assembly of colloidal gold nanoparticles (AuNPs) prepared by laser ablation of a solid gold target in deionized water. Upon addition of formalin, the surface plasmon resonance (SPR) band at 519 nm for pure AuNPs decreases and shifts to red while a new broad SPR band appears at ~700 nm. The red-shift is prominent with increase in the incubation time. The average size of the initial AuNPs is around 12 nm but it increases to 23 nm after addition of formalin. It turns out that formalin acts as a cationic surfactant for AuNPs with negative surface charge in the colloidal solutions. Furthermore, through analysis of the Raman spectrum of formalin and the density functional theory calculations, we confirm that methanediol is the main species in formalin which is in charge of the aggregation of AuNPs.