• Title, Summary, Keyword: photolysis

Search Result 230, Processing Time 0.046 seconds

N(2D) Product Velocity Mapped Imaging in the VUV Photolysis of Nitrous Oxide at 118.2 nm

  • Cosofret, Bogdan R.;Lambert, H. Mark;Houston, Paul L.
    • Bulletin of the Korean Chemical Society
    • /
    • v.23 no.2
    • /
    • pp.179-183
    • /
    • 2002
  • Resonance-enhanced multiphoton ionization with time-of-flight product imaging of the $N(^2D)$ atoms has been used to study the $N_2O$ photodissociation at 118.2 nm and the two-photon dissociation at 268.9 nm. These imaging experiments allowed the determination of the total kinetic energy distribution of the $NO(X^2{\prod})$ and $N(^2D_{5/2})$ products. The $NO(X^2{\prod})$ fragments resulting from the photodissociation processes are produced in highly vibrationally excited states. The two-photon photodissociation process yields a broad $NO(X^2{\prod})$ vibrational energy distribution, while the 118.2 nm dissociation appears to produce a vibrational distribution sharply peaked at $NO(X^2{\prod},\;{\nu}=14)$.

A Study on the Reaction of Icosahedral Carborane with Carbenes

  • Sung, Dae-Dong;Lee, Jae-Duck;Choi, Soon-Kyu
    • Bulletin of the Korean Chemical Society
    • /
    • v.8 no.2
    • /
    • pp.63-68
    • /
    • 1987
  • The photolysis and thermal reaction of hexafluorobenzene solution of icosahedral dicarba-closo-dodecaborane and various carbenes have been shown to lead to the formation of four isomeric insertion products to icosahedral molecules. The results showed the carbene insertion reaction to 1, 2-dicarba-closo-dodecaborane to occur at the positions of 4-, 5-, 7-, and 11-borons, 9-, and 12-borons 3-, and 6-borons and 8-, and 10-borons. The samples of 1, 7-, and 1, 12-dicarba-closo-dodecaborane with carbenes in hexafluorobenzene by photolysis showed no reaction. To find out the reactivities of carbenes to dicarba-closo-dodecaboranes, the total energies have been calculated and have been discussed the tendency for carbene insertion reactions to icosahedral carboranes.

  • PDF

Reaction of Triethylsilyl Radical with Sulfides, a Laser Flash Photolysis Study

  • Platz, M. S.;Lee, Woo-Bung
    • Bulletin of the Korean Chemical Society
    • /
    • v.10 no.5
    • /
    • pp.422-426
    • /
    • 1989
  • Triethylsilyl radical was generated by laser flash photolysis of a 1:1 (v/v)solution of triethylsliance and di-tert-butyl peroxide. The silicon centered radical was reacted with sulfides to give carbon centered radicals by displacement at sulfar. The carbon radicals were readily detected by their transient absorption spectra. The absolute rate of reaction of triethylsilyl radical with 9-fluorenylphenylsulfide, di-n-butylsulfide, di-sec-butyl, di-tert-butyl sulfide and di-n-butyl disulfide are $2.40{\pm}0.12{\times}10^8M^{-1}s^{-1}$, $11.21{\pm}0.89{\times}10^6M^{-1}s^{-1}$, $8.79{\pm}0.73{\times}10^6M^{-1}s^{-1}$, $3.29{\pm}0.18{\times}10^6M^{-1}s^{-1}$, and $3.41{\pm}0.09{\times}10^8M^{-1}s^{-1}$, respectively.

  • PDF

A Study on the Degradation Characteristics of EPN (EPN의 분해특성에 관한 연구)

  • 이용두;김현희;김창영
    • Journal of Environmental Science International
    • /
    • v.11 no.10
    • /
    • pp.1103-1108
    • /
    • 2002
  • In order to evaluate the degradation organophosphorus pesticide, EPN, in water environment, the effects of water temp.(10$^{circ}C,\;30^{\circ}C$), pH(3-11) and sunlight on its degradation were investigated during 10 days. The degradation rate of EPN(200 rpm) was faster at higher water temp. and higher pH, i.e., its degradation rate at pH 3, 5, 7, 9, 11 was 57, 63, 66, 69, 75%(1$0^{\circ}C$), and 70, 74, 79, 91, 97%(3$0^{\circ}C$) after 10 days, respectively. The effect of water temp. on its degradation was little in acidic condition, but was rather great in alkaline condition, with time. EPN was degraded fast at the alkaline condition by photolysis. At the condition of pH 11, EPN was degraded fast at the early stage in the first 2 days, but after that the degradation rate was weakened.

PHOTOCHEMISTRY OF 1-PHENYL-4-(PENTAMETHYLDISILANYL)BUTA-1,2-DIYNE:$[PdCI_2(PPh_3)_2]$-CATALYZED REACTION

  • Lee, Seong-Taek;Baek, Eun-Kyung;Shim, Sang-Chul
    • Journal of Photoscience
    • /
    • v.1 no.2
    • /
    • pp.119-122
    • /
    • 1994
  • $PdCI_2(PPh_3)_2$-catalyzed photolysis of 1-phenyl-4-(pentamethyldisilanyl)buta-1,3-diyne (1) in dry benzene gives 1,4-disilacyclohexa-2,5-diene type dimerization products(3-6) via silacyclopropene. The silacyclopropene is formed from the singlet excited state of 1 and this silacyclopropene reacts with $(PPh_3)_2Pd^0$to form palladasilacyclobutene. In this reaction, the silylene-palladium complex is generated and reacts with 1 to give another silacyclopropene. $PdCI_2(PPh_3)_2$catalyzed photolysis of 1 with other alkynes supports the involvement of this silylene complex.

  • PDF

KINETICS OF ATRAZINE OXIDATION BY UV RADIATION AND OXALATE ASSISTED H2O2/UV PROCESSES

  • Choi, Hyun-Jin;Choi, Jong-Duck;Kim, Hyun-Kab;Lee, Tae-Jin
    • Environmental Engineering Research
    • /
    • v.11 no.1
    • /
    • pp.28-32
    • /
    • 2006
  • The degradation of atrazine was explored using UV alone, $H_2O_2/UV$, oxalate/UV and oxalate-assisted $H_2O_2/UV$. The addition of oxalate to the $H_2O_2/UV$ (oxalate-assisted $H_2O_2/UV$) process was the most effective method for the degradation of atrazine. The overall kinetic rate constant was split into the direct oxidation due to photolysis and that by the radicals from hydrogen peroxide or oxalate. In semi-empirical terms, the initial concentration of hydrogen peroxide had a greater contribution than that of oxalate for atrazine oxidation.

Preparation and Photonic Properties of CNT/TiO2 Composites Derived from MWCNT and Organic Titanium Compounds

  • Oh, Won-Chun
    • Journal of the Korean Ceramic Society
    • /
    • v.46 no.3
    • /
    • pp.234-241
    • /
    • 2009
  • In this study, CNT/$TiO_2$ composites derived from various titanium alkoxides and multiwalled carbon nanotubes (MWCNTs) were synthesized and characterized. Surface areas and pore volumes of the CNT/$TiO_2$ samples showed catastrophic decrease due to deposition of titanium compounds. Scanning electron microscopy (SEM) results indicated that the MWCNTs were homogenously decorated and well-dispersed onto/into the composites without apparent agglomeration of $TiO_2$ particles. In the X-ray diffraction (XRD) patterns, peaks of anatase and rutile phase were observed. The energy dispersive X-ray spectroscopy (EDX) spectra revealed the presence of major elements such as C and O with strong Ti peaks. According to the photocatalytic results, MB removal by a treatment with CNT/$TiO_2$ composites seems to have an excellent removal effect as order of CTIP, CTNB and CTPP composites due to a photolysis of the supported $TiO_2$, the radical reaction and the adsorptivity and absorptivity of the MWCNTs.

Conformational Dynamics of Heme Pocket in Myoglobin and Hemoglobin

  • Kim, Seong-Heun;Heo, Jeong-Hee;Lim, Man-Ho
    • Bulletin of the Korean Chemical Society
    • /
    • v.26 no.1
    • /
    • pp.151-156
    • /
    • 2005
  • The conformational dynamics of heme pocket, a small vacant site near the binding site of heme proteins -myoglobin (Mb) and hemoglobin (Hb), was investigated after photolysis of carbon monoxide from MbCO and HbCO in D$_2$O solution at 283 K by probing time-resolved vibrational spectra of photolyzed CO. Two absorption bands, arising from CO in the heme pocket, evolve nonexponentially in time. The band at higher energy side blue shifts and broadens with time and the one at lower energy side narrows significantly with a negligible shift. These spectral evolutions are induced by protein conformational changes following photolysis that modify structure and electric field of heme pocket, and ligand dynamics in it. The conformational changes affecting the spectrum of photolyzed CO in heme pocket likely modulates ligand-binding activity.