Coauthored Publications with: Hung

Journal Article

Li, H-K, Tsai P-Y, Hung K-C, Kasai T, Lin K-C.  2015.  Communication: Photodissociation of CH3CHO at 308 nm: Observation of H-roaming, CH3-roaming, and transition state pathways together along the ground state surface. Journal of Chemical Physics. 142, Number 4 AbstractWebsite

Following photodissociation of acetaldehyde (CH3CHO) at 308 nm, the CO(v = 1-4) fragment is acquired using time-resolved Fourier-transform infrared emission spectroscopy. The CO(v = 1) rotational distribution shows a bimodal feature; the low- and high-J components result from H-roaming around CH3CO core and CH3-roaming around CHO radical, respectively, in consistency with a recent assignment by Kable and co-workers (Lee et al., Chem. Sci. 5, 4633 (2014)). The H-roaming pathway disappears at the CO(v 2) states, because of insufficient available energy following bond-breaking of H + CH3CO. By analyzing the CH4 emission spectrum, we obtained a bimodal vibrational distribution; the low-energy component is ascribed to the transition state (TS) pathway, consistent with prediction by quasiclassical trajectory calculations, while the high-energy component results from H- and CH3-roamings. A branching fraction of H-roaming/CH3-roaming/TS contribution is evaluated to be (8% ± 3%)/(68% ± 10%)/(25% ± 5%), in which the TS pathway was observed for the first time. The three pathways proceed concomitantly along the electronic ground state surface. © 2015 AIP Publishing LLC.
Veerakumar, P, Panneer Muthuselvam I, Hung C-T, Lin K-C, Chou F-C, Liu S-B.  2016.  Biomass-Derived Activated Carbon Supported Fe3O4 Nanoparticles as Recyclable Catalysts for Reduction of Nitroarenes. ACS Sustainable Chemistry and Engineering. 4:6772-6782., Number 12 AbstractWebsite

Highly porous beetroot-derived activated carbons incorporated with well-dispered magnetite nanoparticles (Fe3O4 NPs; average size ca. 3.8 ± 0.5 nm) were fabricated via a microwave-assisted synthesis route. The magnetic Fe3O4@BRAC catalysts so-fabricated were characterized by a variety of diffent physicochemical teniques, viz. XRD, FE-TEM, VSM, gas physisorption/chemisorption, TGA, XPS, Raman, ICP-AES, and FT-IR spectroscopy. The as-prepared catalysts were exploited for heterogeneous-phase reduction of a series of nitroaromatics (RNO2; R = H, OH, NH2, CH3, and COOH) under KOH as a base, isopropyl alcohol acting as a hydrogen donor as well as solvent and also tested with other solvents. The reaction system not only exhibits excellent activity with high anilines yield but also represents a green and durable catalytic process, which facilitates facile operation, easy separation, and catalyst recycle. © 2016 American Chemical Society.
Hsiao, M-K, Lin K-C, Hung Y-M.  2011.  Quasiclassical trajectory calculations for Li(22PJ) H2 → LiH(X1) H: Influence by vibrational excitation and translational energy. Journal of Chemical Physics. 134, Number 3 AbstractWebsite

Ab initio potential energy surfaces and the corresponding analytical energy functions of the ground 1A′ and excited 2A′ states for the Li(22P) plus H2 reaction are constructed. Quasiclassical trajectory calculations on the fitted energy functions are performed to characterize the reactions of Li(22P) with H2(v 0, j 1) and H2(v 1, j 1) as well as the reaction when the vibrational energy is replaced by collision energy. For simplicity, the transition probability is assumed to be unity when the trajectories go through the crossing seam region and change to the lower surface. The calculated rotational distributions of LiH(v 0) for both H2(v 0, j 1) and H2(v 1, j 1) reactions are single-peaked with the maximum population at j′ 7, consistent with the previous observation. The vibrational excitation of H2(v 1) may enhance the reaction cross section of LiH(v′ 0) by about 200 times, as compared to a result of 93-107 reported in the experimental measurements. In contrast, the enhancement is 3.1, if the same amount of energy is deposited in the translational states. This endothermic reaction can be considered as an analog of late barrier. According to the trajectory analysis, the vibrational excitation enlarges the H-H distance in the entrance channel to facilitate the reaction, but the excess energy may not open up additional reaction configuration. © 2011 American Institute of Physics.
Lin, K-C, Hung K-C, Tsai P-Y, Li H-K.  2014.  Photodissociation of CH3CHO at 248 nm by time-resolved Fourier-transform infrared emission spectroscopy: Verification of roaming and triple fragmentation. Journal of Chemical Physics. 140, Number 6 AbstractWebsite

By using time-resolved Fourier-transform infrared emission spectroscopy, the HCO fragment dissociated from acetaldehyde (CH3CHO) at 248 nm is found to partially decompose to H and CO. The fragment yields are enhanced by the Ar addition that facilitates the collision-induced internal conversion. The channels to CH2CO + H2 and CH3CO + H are not detected significantly. The rotational population distribution of CO, after removing the Ar collision effect, shows a bimodal feature comprising both low- and high-rotational (J) components, sharing a fraction of 19% and 81%, respectively, for the vibrational state v = 1. The low-J component is ascribed to both roaming pathway and triple fragmentation. They are determined to have a branching ratio of <0.13 and >0.06, respectively, relative to the whole v = 1 population. The CO roaming is accompanied by a highly vibrational population of CH4 that yields a vibrational bimodality. © 2014 AIP Publishing LLC.
Tsai, P-Y, Hung K-C, Li H-K, Lin K-C.  2014.  Photodissociation of propionaldehyde at 248 nm: Roaming pathway as an increasingly important role in large aliphatic aldehydes. Journal of Physical Chemistry Letters. 5:190-195., Number 1 AbstractWebsite

Time-resolved Fourier transform infrared emission spectroscopy is employed in the photolysis of propionaldehyde (CH3CH2CHO) at 248 nm to characterize the role of the roaming pathway. High-resolution spectra of CO are analyzed to yield a single Boltzmann rotational distribution for each vibrational level (ν = 1-4) with small rotational and large vibrational energy disposals. A roaming saddle point is found containing two far separated moieties of HCO and CH3CH2 with a weak interaction between them. Quasiclassical trajectory calculations on this configuration yield the CO energy flow behavior, consistent with the findings. The rate constant along the roaming pathway is evaluated to be larger by >1-2 orders of magnitude than those along tight transition state or three-body dissociation pathways. This work implies that the roaming mechanism plays an increasingly important role in aliphatic aldehydes as the molecular size becomes larger. © 2013 American Chemical Society.