Changes between Initial Version and Version 1 of Ticket #169, comment 2

Nov 12, 2015, 8:59:18 PM (5 years ago)
Christof Gessner


  • Ticket #169, comment 2

    initial v1  
     1Collection of arguments and facts:
    13Absorbance is defined as the log of the transmittance. Transmittance is defined as the ratio of received and transmitted radiant flux. As such, Absorbance is a numerical value without a unit.
    35Some numerical scales that are conventionally used are assigned a unit symbol with the value "1", see for example Hounsfield unit "[hnsf'U]". However, such an assignment should only be made when an impact on patient safety is present.
     7Absorbance is not an arbitrary unit - another argument not to use something similar to "A U" here, as it might be misleading and be used with the meaning "arbitrary unit".
     11IUPAC. Compendium of Chemical Terminology, 2nd ed. (the "Gold Book"). Compiled by A. D. McNaught and A. Wilkinson. Blackwell Scientific Publications, Oxford (1997). XML on-line corrected version: (2006-) created by M. Nic, J. Jirat, B. Kosata; updates compiled by A. Jenkins. ISBN 0-9678550-9-8. doi:10.1351/goldbook.
     13Definition of the quantity absorbance, symbol ''A''
     14Logarithm of the ratio of incident to transmitted radiant power through a sample (excluding the effects on cell walls). Depending on the base of the logarithm a decadic and Napierian absorbance are used. Symbols (for the quantity):  ''A'',  ''A_10'',  ''A_e''. This quantity is sometimes called extinction, although the term extinction, better called attenuance, is reserved for the quantity which takes into account the effects of luminescence and scattering as well.