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The branching ratio in the infrared predissociation of aniline-water-methanol<sup>+</sup> ion
Alauddin, Md.,Song, J.K.,Park, S.M. North Holland ; Elsevier Science Ltd 2010 Chemical physics letters Vol.498 No.1
The infrared (IR) photodissociation of aniline-water-methanol cluster ion was investigated in the 2600-3900cm<SUP>-1</SUP> region to examine the factors which play key roles in determining the branching ratio of a concurrent predissociation reaction. The dominant channel in the IR predissociation of AWM<SUP>+</SUP> (A: aniline, W: water, M: methanol) was AWM<SUP>+</SUP>->AM<SUP>+</SUP> at all vibrational modes although the calculated binding energies of water and methanol were nearly the same. Also, the branching ratio was slightly dependent on the specific excited mode, ranging from 0.036 to 0.074; the most effective mode to kick out methanol was OH vibration of methanol.
Infrared predissociation of ternary cluster cations: the solvent effects on the branching ratio
Alauddin, Md.,Song, Jae Kyu,Choe, Joong Chul,Park, Seung Min The Royal Society of Chemistry 2012 Physical chemistry chemical physics Vol.14 No.11
<P>Infrared (IR) predissociation of hydrogen-bonded ternary cluster ions such as aniline–water–ethanol (AWE<SUP>+</SUP>), aniline–water–isopropanol (AWP<SUP>+</SUP>), aniline–methanol–ethanol (AME<SUP>+</SUP>), aniline–water–pyrrole (AWPy<SUP>+</SUP>), and aniline–water–benzene (AWB<SUP>+</SUP>) was examined in the region of 2700–4000 cm<SUP>−1</SUP> to explore the key factors which determine the branching ratios in the concurrent unimolecular dissociation. The smaller solvent molecule was predominantly ejected when the binding energies of the two were not too different. On the other hand, when they were far off, the binding energy also acted significantly on the branching ratio. Besides, mode-selective IR predissociation was observed, while the selectivity was not quite distinct. The IR predissociation of ternary cluster ions bound <I>via</I> hydrogen bonding is considered to occur on a time scale much faster than intramolecular vibrational energy redistribution, which was proved by a statistical transition state theory.</P> <P>Graphic Abstract</P><P>The sizes of solvent molecules as well as their binding energies play a certain role in the infrared predissociation of ternary cluster ions. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c2cp23924h'> </P>
Alauddin, Md.,Park, Jin-Jae,Gwak, Doc-Yong,Song, Jae-Kyu,Park, Seung-Min Korean Chemical Society 2010 Bulletin of the Korean Chemical Society Vol.31 No.4
From time-resolved optical emission spectra, we have investigated the effects of a transverse magnetic field on the expansion of a plasma plume produced by laser ablation of a ZnO:$P_2O_5$ ceramic target in oxygen active atmosphere. The emission spectra of $Zn^{+*}$, $P^{+*}$, and $Zn^*$ neutrals in the presence of magnetic field turn out to be considerably different from those without magnetic field. The characteristics of the deposited films grown on amorphous fused silica substrates by pulsed laser deposition (PLD) are examined by analyzing their photoluminescence (PL), X-ray diffraction (XRD), and UV-visible spectra.
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.
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.
Laser Ablation of a ZnO:P2O5 Target under the Presence of a Transverse Magnetic Field
Md. Alauddin,Jin Jae Park,Doc Yong Gwak,송재규,박승민 대한화학회 2010 Bulletin of the Korean Chemical Society Vol.31 No.4
From time-resolved optical emission spectra, we have investigated the effects of a transverse magnetic field on the expansion of a plasma plume produced by laser ablation of a ZnO:P₂O5 ceramic target in oxygen active atmosphere. The emission spectra of Zn+*, P+*, and Zn* neutrals in the presence of magnetic field turn out to be considerably different from those without magnetic field. The characteristics of the deposited films grown on amorphous fused silica substrates by pulsed laser deposition (PLD) are examined by analyzing their photoluminescence (PL), X-ray diffraction (XRD), and UV-visible spectra.
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.
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.