本實驗使用傅利葉遠紅外線反射光譜以及拉曼散射光譜‚來檢測不同濃度的摻鐵鈮酸鋰在不同溫度下的聲子模。塊材鐵鈮酸鋰的摻鐵濃度分別是: 50ppm、100ppm、300ppm、500ppm及750ppm。
根據群論理論，鈮酸鋰在波向量為零的狀況下有27個振動模，分別是4 A1、5 A1 和9E(其中E振動模簡併數是2) 。拉曼散射光譜儀及傅利葉遠紅外線光譜儀可以測出A1聲子模和E聲子模，本實驗所測出不含鐵鈮酸鋰的A1聲子模如下: 250, 275, 331, 633 cm-1 而E聲子模則分別為157, 172, 235.5, 321.5, 354.7, 439.3, 578 and 625 cm-1 。
經實驗結果發現，含不同濃度鐵的鈮酸鋰其聲子的頻率，似乎沒有什麼變化，這可能是鐵的濃度太小，因此看不出明顯的改變。但是當我們將溫度降到30K 時，在80 cm-1量測到因鐵的加入所產生的聲子，且這個聲子的頻率隨著含鐵的濃度的增加而略為增加，含鐵300ppm 的聲子頻率是81 cm-1、含鐵500ppm 的聲子頻率是82 cm-1、而含鐵750ppm 的聲子頻率則是83 cm-1。參考過去文獻，這個頻率的聲子應該是首次被我們所報告的。此外我們還發現在30K時，含鐵濃度750ppm 的鈮酸鋰中有兩個頻率為236.3 cm-1 和280cm-1 的聲子很清楚的分開來。
在本實驗中無論是利用傅利葉遠紅外線反射光譜儀或是拉曼散射光譜儀均無法測到E-TO5的存在，‚但是文獻上沒有紀錄281 cm-1頻率的聲子卻是被我們量測到了，我們還發現含鐵濃度100ppm 的鈮酸鋰中，E-TO7 移到435.5 cm-1 而其他濃度的樣品E-TO7 的頻率均約在439 cm-1。比較純鈮酸鋰得知，80 cm-1左右的聲子應是由於摻鐵的緣故，而281cm-1左右的聲子來源則有待近一步研究。

Abstract
We study the LiNbO3 (Fe – doped) crystals by Infrared absorption spectra and Raman scattering. The samples were Fe-doped with 000ppm, 050ppm, 100ppm, 300ppm, 500ppm and 750ppm.
According to the group theory, There are 27 vibration modes for pureLiNbO3 at zero wave vector, which are divided as 4A1、5A2, and 9E modes (E modes degenerate into 2). Whereas A1 modes and E modes are both Raman and infrared active, A2 modes are Raman and infrared inactive.
In our experiment, the modes of A1 group are found as 250, 275, 331, 633 cm-1 and the modes of E are found as157, 172, 235.5, 321.5, 354.7, 439.3, 578 and 625 cm-1, All these modes corresponding to the group theory.
In our study, different concentrations of iron doped LiNbO3, almost do not have obvious change in the frequencies of the phonon modes. It may be due to the small concentrations of doped iron. In our experiment, when the temperature was lowered to 30K, an impurity mode around 80cm-1 appeared. This is the first report in the infrared study . The frequency of this impurity mode is 81cm-1 for 300ppm iron-doped LiNbO3, 82 cm-1 for 500ppm iron-doped LiNbO3 and 83 cm-1 for 750ppm iron-doped LiNbO3. At 30 K, lines 236.3 cm-1 and 280 cm-1 were clearly separated only in 750 ppm sample.
The mode E-TO5 calculated by by Caciuc et al. 15 is 334 cm-1 and is
419 cm-1 by Parinski et al. 16 was
not found neither in our experiment nor in the literature . According to the literature, the mode 281 was not reported neither by theory nor by experiment reports. We also found E-TO7 shift to 434.5 cm-1 of 100 ppm doped sample, ( for other concentration sample, E-TO7 is around 439 cm-1）

1. 陳清嶺 國立台灣師範大學物理研究所1998年碩士論文
2. 錢玉坤 國立台灣師範大學物理研究所1998年碩士論文
3. R.S.Weis, T.K.Gaylord, Appl. Phys. A: Solids Surf.37,191（1985）
4. Shiuan Huei Lin,Mei Li Hsieh, and Ken Yuh Hsu, J. Opt. Soc.Am. B/Vol.16,No16.7/July 1999
5. Chunhui Yang*, Yequan Zhao, Rui Wang, Minghua Li, Optics Communication 175(2000) 247-252
6. W.Y. Ching, Zong-Quen Gu, and Yong-Nian Xu, Phys. Rev. B V50 n 3 1992- (1994)
7. S.C.Abrahams, J.M.Reddy, J.L.Bernstein, J.Chem.Phys.Solds 27,997（1966）
8. V. Caciuc, A. V. Postnikov, G. Borstel,Physical review v 61, 8806
(2000)
9. S.C.Abrahams, W. C.Hamilton, J. M. Reddy: J. Chem.Phys.Solds 27,1019-1026（1966）
10. S.C.Abrahams, E.Buehler, W. C.Hamilton,S.J.Laplaca: J.Chem.Phys.Solds 34,521-532（1973）
11. R.C.Duvarney and S. Perkowitz, Int. J. Infrared Millimeter Waves 2,587(1981)
12. R.J. Bell, Introductory Fourier Transform Spectroscopy (Academic Press, New York,1972 )
13. J. Connes. Aspen Int. Conf. on Fourier Spectroscopy 83 (1970)
14. I. R. Bracewell, The Fourier Transform and It’s Application (MCGraw-Hill, New York,1965)
15. S.Perkowitz, Optical Characterization of Semiconductors (Academic après, San diego,1993 ) chapter 1
16. K. Parlinski, Z. O. Li, and Y. Kawazoe, Phys. Rev. B 61,272(2000)
17. A Ridah, P. Bourson ,M.D. Fontana, and G. Malovichko, J. Phys. : Condens.Matter 9,9687(1997)
18. S. Kojima, Jpn. J. Appl. Phys., Part 1 32,4373（1993）
19. M.R. Chowdhury, G. E. Peckham, and D. H. Saunderson, J. Phys. C 11, 1671（1978）
20. A Ridah, M.D. Fontana, and P. Bourson, Phys. Rev. B 56,5967（1997）
21. Y.Repelin,E. husson,F. Bennani,and C.Proust,J.Phys.Chem. Solids 60, 819
（1999）
22. Charles Kittel : “Introduction to Solid State physics “(7th edition)
23. A.V. Postnikiv, V. Caciuc, and G. Borstel, J.Phys. Chem. Solids 61,295（2000）
24. S. Odoulov, T.Tarabrova, and A. Shumelyuk, I.I. Naumova, and T.O. Chaplina, Physical Review lellers, v 84, n 15,3294- (2000)
25. K.Chah , M.Aillerie , M.D. Fontana , G. Malovichko, Optics Communication 176(2000) 261-265
26. The Ramman effect ,v 1, A.Anderson(1971)
27. The Physics of phonon, G P Srivastava(1990)
28. U. T. Schwarz and Max Maier, Phys. Rev. B, v 55, n 17, 11041-(1997)
29. “Applied Group Theory for Physicists and Chemists”, George H. Duffey