Lab 2111 Nexus 670 and Magna 560
Instructions
To sign on the computer, USER: Student Password: organic
Plea write your name and other information in the Logbook. Plea notify Scott Taylor of problems ext 51806
The Nexus 670 should always be on. Check LEDS on the top left of the instrument, all should be on, with scan light blinking.
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Click on either icon for "Omnic ESP". At this point you can also u the Help menu for further information in addition to the instructions. See “Getting Started” in the help menu.
There is a green check mark and the words Bench Status which shows that the interferometer and the computer are connected and the optics are working. If there is no icon there, there is no communication between the computer and interferometer. Sometimes there is a few minutes delay while the program is initializing.
Go to Collect, Experiment Setup, Bench, to obrve the interferogram. In the middle of the display is
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a characteristic signal maximum. Check to e if the interferogram signal is within limits, (min 2, max 9.8) if it is a flat line go to Collect, Diagnostics and click on Ret Bench. With a gain of 1 (t by going to the Bench Tab in Experiment Setup) check the p-p voltage-it should be greater than 8 volts. This is with no accessories and a clear path in the sample compartment. Also be sure the aperture is t to 100, normal for resolution 4. A smaller resolution will automatically t the aperture smaller. This means the interferogram peak-to-peak voltage will be smaller.大学长
Interferogram Display
Also in the window below different detectors can be lected. The room temperature detector is DTGS KBr. This is the default detector and normally ud.
Normally the transmission holder should be in the sample chamber. If you u another sample module, such as the ATR module, plea carefully clean it and put it back in the cabinet. NEVER LEAVE THE SAMPLE CHAMBER OPEN WHEN YOU LEAVE THE LAB. The sample chamber is purged in addition to the instrument, and helps prerve the windows. If you accidentally leave the door on the chamber open veral days, it shortens the life of the windows unnecessarily. Also, the ATR module is extremely expensive and shouldn’t be left outside of its box and cabinet.
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Go to Collect, Experimental tup to lect number of scans, default 32, resolution default 4, absorbance or transmission, correction for CO2 and others, and other options.
It is usually t up for the simple transmission experiment.
Background:
Collect background first with no sample. This will give a characteristic background in transmission mode with no sample as shown below. This shows the instrument operating normally.
Before collecting data, create a background with the solvent, pure KBr pellet or blank KBr or NaCl window so this will be subtracted from sample respon. Inrt the blank KBr pellet, KBr or NaCl window in the sample holder. Choo Collect Background from the Collect Menu, or click on the Collect Background
button on the toolbar.
When the collection is finished, you can save the background to a window if you want it available later for a background handling option, or simply clo the Collect Background window. The spectrum is not saved then, but remains the current background. This step eliminates the background characteristics of the spectrometer so the peaks in the final spectrum are due solely to the sample.
Collecting Sample:
鱼皮怎么做好吃又简单The sample chamber holder holds standard transmission sample cards and liquid sample cells.
Install your sample in the light path, taking care not to spill anything inside the sample compartment. This can be a liquid sample cell, a KBr or NaCl window. The red lar spot will rve to locate the measurement path, it comes from the right side of the sample compartment.
Avoid looking directly or at reflections from this lar and the invisible infrared beam.独一无二霸气签名
U Collect Sample in the Collect menu to collect the spectrum of a sample, or click on the Collect Background button on the toolbar. There is a progress indicator bar on the lower left hand side of the screen. The spectrum of the sample will be ratioed against the single-beam spectrum of the background.
The result below is a polystyrene film. For a film, the background is air or purge
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Edit Menu
This allows you to change the size of the annotation numbers when printing, Collect Menu汉代的皇帝
This can bring up “experiment tup”, with ability to change number of scans and resolution. Final format can be absorbance or transmission. There is a box to check “save interferogram” to have the ability to process the spectrum later. Corrections that can be made later include one for ATR wavelength dependence of attenuated total reflection. Background handling determines when and how
often background is taken. Also you can u a saved background file.
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