Dear Sir. Concerning your issue about the Fe-S vibrational feature from FTIR analysis

 . Although commercial infrared spectrometers that operate in the region below 400 cm-' in which sulphides mostly absorb have only r~cently become available, there is already ~ considerable amount of information publisheg on this mineral group. The fullest survey has been undertaken by~ovarennykh and coworkers (1971a, 1971b, 1973, 1974), who give spectra of nearly 60 sulphides and sulphosalts, and six arsemides in the 500-60 cm -I region. Liese (1974) lists absorption maxima in the 435-250 am-' region for 44 sulphides, six arsemides, two tellurides and one antimomide. Nyquist and Kagel (1971) give spectra down to 45 cm-' of 17 synthetic sulphides, ~ selenides, and eight tellurides. Other workers have pubfished data on more limited groups of compounds (Earr and Kovach, 1969; Porneris, 1969; Whitfield, 19711Byer et ~., 1973; Petzelt and Grlgas, 1973; Lutz and Willich, 1974.) All these papers inclnde powder transmission spectra, which are moe~ directly useful for characterization. Single crystal reflection spectra have also been obtained, and although essential for fundamental vibrational assignments in complex spectra, they are inconvenient or even impossible to obtain from many natural samples. Unfortunately, comparison of data on the same ~inerals published by different authors often shows substantial discrepancies which prevent confident application of these results for identification purposes. Such discrepancies may have several origins: they may arise from misidentifleations or from impurities in the minerals examined, or they may reflect the reel variations i~ composition, structure or crystallinlty that can occur within the range of a single mineral species. They can also have an instramsntal origin, as many spectrometers operate at close %o their practical limits in this low energy region of th~ infrared spectrum. To resolVe some of these uncertainties, a survey of the spectra of a number of carefully purified and characterized sulphide minerals has been tuldertsken using a Beckman-RIIG Model FS 720 Fourier-Transform Interferometer- This instrument was found to give trustworthy results over the region 420~00 cm-' mith resolution of about ~-4 am-' using a single beam splitter. The region below I 00 cm was found to exhibit at mo~t only weak absorption b~s of little value for ~harecterizablon purposes and was net examined in detail, although potentially accessible on the interferometer.. I think the following below links may help you in your analysis:

http://www.minersoc.org/pages/Archive-MM/Volume_42/42-322-277.pdf

http://www.minsocam.org/ammin/AM49/AM49_1670.pdf http://pubs.acs.org/doi/abs/10.1021/ja00192a002?journalCode=jacsat

Thanks

Thank you very much Isam Eldin Hussein Elgailani sir for your valuable informations. these informations definitely help me in sort out the difficulty  in assigning the IR bands. Thanks

Dear Sir, Ithing the following article maz help You, One-step synthesis of cubic FeS 2 and flower-like FeSe 2 particles by a solvothermal reduction process

B Yuan, W Luan, S Tu - Dalton transactions, 2012 - pubs.rsc.org

Thank you very much for your suggestion dear Milorad Cakic sir.Thank you