IR Absorption Spectroscopy

___ refers to the part of the infrared spectrum that is closest to VISIBLE LIGHT and ___ refers to the part that is closer to the MICROWAVE region mid IR region ____ mm however, when it comes to wavenumber it extends to the range of ____

IR Active species Molecular species with ___ between various VIBRATIONAL and ROTATIONAL states (___) ONLY BONDS with significant ___ will absorb INFRARED RADIATION

Bonds which DO NOT absorb infrared include: (2)

____ like ___ and ___ absorb only in the FAR IR REGION ( <700 cm^-1) so are suitable only as SAMPLE HOLDERS for most MID-IR measurements

IR RADIATION IS PASSED THROUGH A SAMPLE. Some of the infrared radiation is____ , the rest is ____. The resulting spectrum represents the MOLECULAR ABSORPTION and TRANSMISSION, creating a MOLECULAR FINGERPRINT of the sample. NONE of two unique molecular structures PRODUCE THE SAME infrared spectrum —This makes infrared spectroscopy useful for several types of analysis.

SAMPLE HANDLING: True or False: Good solvents that are transparent throughout the region of interest allow for ease in sample handling

SAMPLE HANDLING: The spectrum of a low-boiling liquid or gas can be obtained by permitting the sample to: EXPAND into an ___ equipped with SUITABLE WINDOWS

SAMPLE HANDLING: Cells: ___ are most commonly employed; even with care, however, their surfaces eventually become fogged due to absorption of moisture. Polishing with a ___ returns them to their original condition.

SAMPLE HANDLING: Liquids: When the amount of liquid SAMPLE IS SMALL or when a suitable SOLVENT UNAVAILABLE, it is common practice to obtain spectra on ___. A drop of the (answer above) is squeezed between two ___ to give a layer that has a thickness of ___. The two plates, held together are then mounted in the beam path. Such a technique DOES NOT GIVE REPRODUCIBLE ____ HOWEVER, SPECTRA are usually SATISFACTORY for QUALITATIVE INVESTIGATIONS

SAMPLE HANDLING: Solids: Most ORGANIC COMPOUNDS exhibit NUMEROUS ABSORPTION PEAKS throughout the ____, BECAUSE OF THAT FINDING A SOLVENT WITHOUT ____ IS IMPOSSIBLE. As a consequence, spectra are often obtained on DISPERSIONS OF THE SOLID in a ____ or ____

SAMPLE HANDLING: Pelleting: One of the most popular techniques for handling solid samples has been ___. Milligram or less of the finely ground sample is intimately mixed with about ____. The mixture is then pressed in a die at ___to yield a ___ DISK. The DISK is then held in the INSTRUMENT BEAM FOR SPECTROSCOPIC EXAMINTION for spectroscopic examination.

SAMPLE HANDLING: Mulls: Infrared spectra of solids that are NOT SOLUBLE IN AN INFRARED-TRANSPARENT SOLVENT or are NOT CONVENIENTLY PELLETED in KBr are often obtained by: DISPERSING THE ANALYTE in a ___ or ___. Mulls are formed by grinding ___ of the FINELY POWDERED SAMPLE in the presence of ____. The resulting mull is then examined as a FILM between flat ___.

Aside from Mid IR being the most widely used The NEAR-INFRARED region from 4000 to 14,000 cm-1 (0.75 to 2.5 mm) also finds considerable use for the ____ The FAR-INFRARED region has been for the determination of the structures of ____

Virtually all infrared instrument manufactures now offer ____ to assist chemist in identifying compounds from stored infrared spectral data a peak profile,can be compared with profiles of pure compounds stored.

Difference between Infrared Absorption and Ultraviolet/Visible Spectroscopic methods (3)

FITR Spectrometer steps (single beam)

Applications of Infrared Analysis (9)