Cooling using shaped pulses

The dispersion of Pt was determined from the amount of chemisorbed CO using pulse method. The experiments were carried out using a (Micromeritics 2910 AutoChem) instrument. The Pt modified catalysts were reduced with hydrogen in a U- shaped quartz tube and then cooled to 313 K under flow of He and CO pulse chemisorption was performed. More detail description of the R dispersion can be found in reference [11], The dispersion of R measured by CO chemisorption was the highest for R-MCM-41 catalyst prepared by ion-exchange method Table 1. 

To detect the X-rays emerging from the sample, a solid state Si(Li) detector, cooled to liquid nitrogen temperature, is used to detect the characteristic X-rays. The detector has a resolution of about 160 eV at 5.9 keV. The pulses from the detector are processed by a shaping amplifier and converted into pulse height by the analog-to-digital converter (ADC) of the multichannel analyzer (MCA). 

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