ABSTRACT Previous workers have investigated the reaction of tetrachloroethene using thermal initi... more ABSTRACT Previous workers have investigated the reaction of tetrachloroethene using thermal initiation and CO2-laser initiation via sensitizing species. In both instances, the principal product was found to be hexachlorobenzene. One group reported evidence of laser specificity in this reaction, in that BCl3 acted as a sensitizer to produce hexachlorobenzene as the principal product, but SF6 and BBr3 did not. We have found that specificity is highly dependent on reaction conditions. We reproduced the previous results using similar experimental conditions, but under different conditions, we found that the specificity is lost, with all three sensitizers which we used (BCl3, SF6, and SiF4) sensitizing the reaction to produce mainly hexachlorobenzene. There were some differences among the sensitizers, as, for example, the fact that SF6 produced the most nearly pure hexachlorobenzene product.
Fluorescence of the Na* (3p2P) D lines is observed upon photodissociation of NaI vapor by 1900–25... more Fluorescence of the Na* (3p2P) D lines is observed upon photodissociation of NaI vapor by 1900–2500 Å radiation obtained through a monochromator from a high current, low pressure H2 arc continuum source; the properties of this source are briefly described. The D lines fluorescence efficiency exhibits a threshold at ∼ 2500 Å, a relative maximum at ∼ 2225 Å, and a relative minimum at ∼ 2050 Å. An expression is derived for the distribution in laboratory speeds of an atom produced by photodissociation of a diatomic molecule at thermal equilibrium. This expression is then employed to calculate the distributions in speeds of the photodissociatively generated Na* and these computed Na* speed distributions are employed to analyze the observed attenuations of the D-lines fluorescence upon addition of foreign gases. In this manner, the dependences on relative collision velocity g of the cross sections Qq for collisional quenching of Na* by CO2, C2H4, CH3CN, CF3Cl, C6H6, SO2, and I2 have been determined. Over the range in g studied in this work (∼ 1.0 - 2.5 km∕sec), Qq varies approximately as g−4∕8, with s in the range of 4–6, for all seven quenching gases. At a fixed value of g, Qq varies as: I2 > SO2> C6H6 >CH3CN> CF3Cl>C2H4 > CO2. These results on the quenching cross sections are discussed in terms of the long-range forces between the reactants, including a possible long-range electron transfer curve crossing for the collision of Na* with I2 or SO2. These measured quenching cross sections are also compared with previous literature values; good agreement is found in most cases, although some discrepancies are noted.
Page 1. edited bv computer series, 1 68 JAMES P. BIRK Arizona State University Tempe. AZ 85287-1 ... more Page 1. edited bv computer series, 1 68 JAMES P. BIRK Arizona State University Tempe. AZ 85287-1 604 Teaching Practical Computer Skills to Chemistry Majors Boyd L. Earl, David W. ~merson,' Brian J. Johnson, and Richard ...
• CHED technical sessions will be in the Clarion Hotel, 616 Convention Way; morning sessions will... more • CHED technical sessions will be in the Clarion Hotel, 616 Convention Way; morning sessions will begin at 8:30 am and afternoon sessions at 1:30 pm unless otherwise noted here or in the final program. Tickets to the CHED dinner (Saturday evening, March 27; event #101, $55) ...
Page 1. 2184 BL EARL, B. K. HILL, AND JM SHREEVE Inorganic Chemistry TABLE I POWDER SPECTRA FOR N... more Page 1. 2184 BL EARL, B. K. HILL, AND JM SHREEVE Inorganic Chemistry TABLE I POWDER SPECTRA FOR NOS03CF3a d Spacings from Lines in X-ray Powder Photograph _____-_---Sample prepared by ___-_____ 7 --Method I---Method 11-- --Method I---RIethod ...
ABSTRACT Previous workers have investigated the reaction of tetrachloroethene using thermal initi... more ABSTRACT Previous workers have investigated the reaction of tetrachloroethene using thermal initiation and CO2-laser initiation via sensitizing species. In both instances, the principal product was found to be hexachlorobenzene. One group reported evidence of laser specificity in this reaction, in that BCl3 acted as a sensitizer to produce hexachlorobenzene as the principal product, but SF6 and BBr3 did not. We have found that specificity is highly dependent on reaction conditions. We reproduced the previous results using similar experimental conditions, but under different conditions, we found that the specificity is lost, with all three sensitizers which we used (BCl3, SF6, and SiF4) sensitizing the reaction to produce mainly hexachlorobenzene. There were some differences among the sensitizers, as, for example, the fact that SF6 produced the most nearly pure hexachlorobenzene product.
Fluorescence of the Na* (3p2P) D lines is observed upon photodissociation of NaI vapor by 1900–25... more Fluorescence of the Na* (3p2P) D lines is observed upon photodissociation of NaI vapor by 1900–2500 Å radiation obtained through a monochromator from a high current, low pressure H2 arc continuum source; the properties of this source are briefly described. The D lines fluorescence efficiency exhibits a threshold at ∼ 2500 Å, a relative maximum at ∼ 2225 Å, and a relative minimum at ∼ 2050 Å. An expression is derived for the distribution in laboratory speeds of an atom produced by photodissociation of a diatomic molecule at thermal equilibrium. This expression is then employed to calculate the distributions in speeds of the photodissociatively generated Na* and these computed Na* speed distributions are employed to analyze the observed attenuations of the D-lines fluorescence upon addition of foreign gases. In this manner, the dependences on relative collision velocity g of the cross sections Qq for collisional quenching of Na* by CO2, C2H4, CH3CN, CF3Cl, C6H6, SO2, and I2 have been determined. Over the range in g studied in this work (∼ 1.0 - 2.5 km∕sec), Qq varies approximately as g−4∕8, with s in the range of 4–6, for all seven quenching gases. At a fixed value of g, Qq varies as: I2 > SO2> C6H6 >CH3CN> CF3Cl>C2H4 > CO2. These results on the quenching cross sections are discussed in terms of the long-range forces between the reactants, including a possible long-range electron transfer curve crossing for the collision of Na* with I2 or SO2. These measured quenching cross sections are also compared with previous literature values; good agreement is found in most cases, although some discrepancies are noted.
Page 1. edited bv computer series, 1 68 JAMES P. BIRK Arizona State University Tempe. AZ 85287-1 ... more Page 1. edited bv computer series, 1 68 JAMES P. BIRK Arizona State University Tempe. AZ 85287-1 604 Teaching Practical Computer Skills to Chemistry Majors Boyd L. Earl, David W. ~merson,' Brian J. Johnson, and Richard ...
• CHED technical sessions will be in the Clarion Hotel, 616 Convention Way; morning sessions will... more • CHED technical sessions will be in the Clarion Hotel, 616 Convention Way; morning sessions will begin at 8:30 am and afternoon sessions at 1:30 pm unless otherwise noted here or in the final program. Tickets to the CHED dinner (Saturday evening, March 27; event #101, $55) ...
Page 1. 2184 BL EARL, B. K. HILL, AND JM SHREEVE Inorganic Chemistry TABLE I POWDER SPECTRA FOR N... more Page 1. 2184 BL EARL, B. K. HILL, AND JM SHREEVE Inorganic Chemistry TABLE I POWDER SPECTRA FOR NOS03CF3a d Spacings from Lines in X-ray Powder Photograph _____-_---Sample prepared by ___-_____ 7 --Method I---Method 11-- --Method I---RIethod ...
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