Difference spectrum using DRIFT

Vertical surface collectors can readily provide information on relative drift (e.g., the amount of drift from one field trial compared to another). However, it is difficult to obtain absolute data unless the precise collection characteristics are known for the droplet size spectrum at the point of spray collection, wind speed and air turbulence intensity. " The SDTF conducted studies in wind tunnels to compare the collection efficiency of different types of drift collector used in its field studies. These studies showed that collection efficiency on strings was several orders of magnitude higher for 0.8-mm diameter cotton string than for 2-mm diameter polyethylene line and vertical o -cellulose strips or squares. The higher collection efficiency for the cotton... 

FTIR data analysis software enables spectral data for the imcoated filler to be subtracted from that of the coated specimen, thus creating a difference spectrum that enhances absorption bands associated only with the surface treatment. It is important to point out that subtraction does not always yield additional information, especially when a small absorption associated with a surface treatment is obscured by a large absorption associated with the filler. Spectral changes relative to the unhound surface treatment/additive provide insight into the natnre of interaction with the surface. Examples of use of DRIFTS are described in Section 3.5.4.4. DRIFTS spectra can be quantified provided sample preparation/presentation and representation of the data is correct. 

These spectra were converted from. ras to. abs files with no change in the Y-axis scale and then used to search Sadtler libraries of commercial material using Mattson First software with a correlation coefficient search algorithm which takes into account baseline drift and differences in scaling. As can be seen the sample spectrum and the library spectrum are usually quite similar. The library spectra shown here were the best hits in each of the searches with a search correlation coefficient of >0.9 with 1.0 representing a perfect match. 

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