• Analytical Science and Technology
• /
• v.26 no.4
• /
• pp.235-244
• /
• 2013

Detection of halogens using laser-induced breakdown spectroscopy (LIBS) in open air is very difficult since their strong atomic emission lines are located in VUV region. In NIR region, there are other emission lines of halogens through electronic transitions between excited states. However, these lines undergo Stark broadening severely. We report the observation of the emission lines of halogens in laser-induced plasma (LIP) spectra in NIR region using a helium gas flow. Particularly, the emission lines of iodine at 804.374 and 905.833 nm from LIPs have been observed for the first time. In the helium ambient gas, Stark broadening of the emission lines and background continuum emission could be suppressed significantly. Variations of the line intensity, plasma temperature, and electron density with the helium flow rate was investigated. Detection of chlorine and bromine in flame retardant of rubbers was demonstrated using this method. Finally, we suggest a pulsed helium gas jet as a practical and ecomonical helium gas source for the LIBS analysis of halogens in open air.

• Journal of the Korean Chemical Society
• /
• v.7 no.2
• /
• pp.179-181
• /
• 1963

The partition function of liquid halogens is developed applying the significant liquid structure theory proposed by H. Eyring and co-workers. The parameters in the partition function are determined by triple point technique which was proposed by the authors in the previous paper, and also the thermodynamic properties and the surface tension are calculated by the method therein.

• Proceedings of the Korean Vacuum Society Conference
• /
• 1994.02a
• /
• pp.4-4
• /
• 1994

• Bulletin of the Korean Chemical Society
• /
• v.3 no.4
• /
• pp.133-139
• /
• 1982

It has been presumed that the molten sulfur above $159^{\circ}C$ consists of an equilibrium mixture of $S_8$ rings and $S_x$ polymers where the number average degree of polymerization, P, is large. But it is known that admixture of halogens with liquid sulfur greatly reduce the viscosity. Constructing a new equilibrium equation, it is possible to evaluate the viscosity when halogens are added to liquid sulfur. Calculated viscosity is in good agreement with experimental values. Using the proposed model, the thermodynamic properties of liquid sulfur are also calculated over a wide range of temperature which the sulfur exists as the polymer.

• Journal of the Korean Chemical Society
• /
• v.9 no.4
• /
• pp.169-173
• /
• 1965

The results of ultraviolet spectrophotometric investigations on the system of chlorobenzene with iodine, chlorine and iodine monobromide in carbon tetrachloride at $25^{\circ}$ indicate the formation of one to one molecular complexes, $C_6H_5Cl{\cdot}I_2,\;C_6H_5Cl{\cdot}Cl_2\;and\;C_6H_5Cl{\cdot}IBr.$ The equilibrium constants obtained at $25^{\circ}$ for the complex formations are 0.106, 0.0400 and 0.109 $lmole^{-1}$, respectively. These results combined with those reported in the literature reveal the following order as the relative stabilities of complexes with aromatics and with halogens or interhalogens, respectively. $ICl>IBr>I_2>Br_2>Cl_2$. Benzene>Chlorobenzene.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2000.02a
• /
• pp.146-146
• /
• 2000

We have studied the etching of Si(100)-2xl by Cl and Br, using scanning tunneling microscopy to obtain morphological information that can be related to reaction and desorption pathways. Clean surfaces were exposed to molecular halogens at room temperature to produce well-defined chemisorption structures for coverages in the range 0.2-1.0 ML. Heating to 750-750 K induced etching by thermal desorpton. Analysis of the halogen concentration before and after heating indicated that the rates of desorption for SICl2 or SiBr2 were greatest for intermediate coverages and that etching was suppressed as saturation was reached. Hence, desorption is not simply proportional to the concentration of species that can form adsorbed precursors SiX2(a). Instead, it is directly coupled to the creation of monomer vacancies adjacent to the SiX2 (a) unit because this increases the lifetime of the excited state and increases the likelihood of its desorption. Increasing the surface concentration of halogens reduces the rate of vacancy formation. We show that these rates are also affected by a re-dimerization process in the high temperature Br-stabilized Si(100)-3xl reconstruction that increases the likelihood of siBr2(a) formation and enhances its desorption. I will also discuss recent result for F etching on Si(100)-2xl.

• Proceedings of the Korea Air Pollution Research Association Conference
• /
• 2000.04a
• /
• pp.323-324
• /
• 2000

최근 대기 중에 부유하는 입자상 물질의 농도와 인간의 질병 및 사망률에 관한 역학적 조사가 진행되면서 대기 중 입자상 물질 측정에 많은 관심이 집중되고 있다. 이러한 입자상 물질 중 $Cl^{-}$, $Br^{-}$ 등, 할로겐족의 분석은 일반적으로 이온크로마토그래피법(IC)으로 수행되고 있으나, 최근에는 금속원소 분석에 사용되는 ICP-AES(Inductively Coupled Plasma Atomic Emission Spectrometry)를 이용하여 분석하기도 하는 것으로 알려져 있다. (중략)

• Korean Journal of Pharmacognosy
• /
• v.7 no.3
• /
• pp.159-169
• /
• 1976

The present review records the known structures of more than 80 organic compounds containing halogens, which may be considered naturally occurring. The format of the review is based on the viewpoint of biochemists. Compounds containing one type of halogen atom have been placed in one of four major division, i.e., structures possessing fluorine, chlorine, bromine or iodine covalently bonded to carbon. Within each major division molecular structures are given along with the species from which the compounds have been isolated, The biological significance, if any, is also mentioned.

• Bulletin of the Korean Chemical Society
• /
• v.16 no.4
• /
• pp.349-355
• /
• 1995

Bromo-and chlorotrimethylsilane react with selenium dioxide in halocarbon solvents and generate selenium oxybromide and oxychloride, respectively. These in-situ generated oxyhalides turned out to be very efficient for selective bromination and chlorination of aldehydes and ketones. Under carefully controlled reaction conditions, second and third introduction of halogens into carbonyl compounds can be greatly suppressed, and high yields of monohalo compounds were obtained. The product ratios of this halogenation reactions can be best explained if the reactions are assumed to involve intermediate β-ketoselenenyl chlorides.

• Environmental Engineering Research
• /
• v.11 no.2
• /
• pp.84-90
• /
• 2006

UV-catalytic oxidation technique was applied for the treatment of bio-refractory character of the leachate, which is generally present in the form of adsorbable organic halogens (AOX). Destruction of AOX was likely to be governed by pH adjustment, quantitative measurement of oxidants, and the selection of oxidation model type. Peroxide induced degradation ($UV/H_2O_2$) facilitated the chemical oxidation of organic halides in acidic medium, however, the system showed least AOX removal efficiency than the other two systems. Increased dosage of hydrogen peroxide (from 0.5 time to 1.0 time concentration) even did not contribute to a significant increase in the removal rate of AOX. In ozone induced degradation system ($UV/O_3$), alkaline medium (pH 10) favored the removal of AOX and the removal rate was found 11% higher than the rate at pH 3. Since efficiency of the $UV/O_3$ increases with the increase of pH, therefore, more OH-radicals were available for the destruction of organic halides. UV-light with the combination of both ozone and hydrogen peroxide ($UV/H_2O_2$ 0.5 time/$O_3$ 25 mg/min) showed the highest removal rate of AOX and the removal efficiency was found 26% higher than the removal efficiency of $UV/O_3$. The system $UV/H2O_2/O_3$ got the economic preference over the other two systems since lower dose of hydrogen peroxide and relatively shorter reaction time were found enough to get the highest AOX removal rate.