Spectrum acquisition frequency locks

The prism at the outlet of the laser serves to separate the laser emission of the gas fluorescence and allows for a clean excitation of the sample. For excitation using solid-state lasers, this element is dispensable. The lens (element 5) collects the fluorescent signal and focuses on the aperture of the monochromator. The filter is used to eliminate excitation that is spread over the surface of the sample. The optical chopper serves to modulate the light at a defined frequency, which serves as reference for the lock-in amplifier. A data acquisition system controls the pace of the monochromator and reads the signal of the lock-in, generating the sample s emission spectrum. 

The proton NMR spectrum of the Me2S0 extract of the lignite was obtained using a XL-200 Fourier transform proton NMR spectrometer. Details of lignite extraction with Me2S0 are described elsewhere (, 5). Instrumental conditions for the measurement of the spectrum were as follows frequency - 200 MHz proton sample state - liquid solution solvent - Me2S0-dg locked sample concentration - ca. 200 mg/10 ml probe temperature - 25 C sweep width - 2600.1 Hz acquisition time - 1 second internal reference - tetramethyl silane number of transients - 1500 pulse width - 5.0 piseconds. 

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