Convenient new chemical actinometer based on aqueous acetone, 2-propanol, and carbon tetrachloride.
A convenient new chemical actinometer was developed to measure the spectral output of laboratory ultraviolet (UV) light sources over the wavelength range of 260-330 nm. It can also be used to measure solar UV irradiance (< or =325 nm). The actinometer is based on the photoreduction of aqueous carbon tetrachloride (CT) to chloroform (CF) in the presence of acetone (the chromophore) and 2-propanol (the reductant). In all cases, CT disappearance (and CF formation) followed zero-order kinetics over 95% of the reaction. The slope of the linear decay curve forms the basis of the new actinometer, which was calibrated using ferrioxalate actinometry. Quantum yields were measured at 10 nm intervals and were found to be uniform throughout the range of 260-300 nm. As expected, quantum yields gradually decreased to zero asthe wavelength was increased from 300 to 340 nm. The high quantum yields (approximately 150), low sensitivityto room light, and the straightforward determination of [CT] and [CF] by gas chromatography offer significant advantages over some other chemical actinometers, which might require the preparation and purification of light-sensitive compounds in a darkened environment and long exposure times.
Li
Heng
H
Department of Civil and Environmental Engineering, University of Michigan, Ann Arbor, Michigan 48109, USA.
Betterton
Eric A
EA
Arnold
Robert G
RG
Ela
Wendell P
WP
Barbaris
Brian
B
Grachane
Cecilio
C
D019840:2-Propanol / Q000737:chemistry*; D000096:Acetone / Q000737:chemistry*; D002251:Carbon Tetrachloride / Q000737:chemistry*; D002849:Chromatography, Gas; D007700:Kinetics; D010777:Photochemistry / Q000295:instrumentation* / Q000379:methods; D013057:Spectrum Analysis / Q000295:instrumentation* / Q000379:methods; D014466:Ultraviolet Rays
D000096:Acetone; D002251:Carbon Tetrachloride; D019840:2-Propanol