红外光谱FTIR.ppt

红外光谱红外光谱的基本概念红外光谱的基本概念分子振动的类型

双原子分子振动
中红外区的频率常用波数ν表示，波数的单位是cm-1，标准红外谱图标有频率和波长两种刻度。波长和波数的关系是：http://bbs.elecfans.com电子技术论坛http://www.elecfans.com电子发烧友各种振动方式及能量振动自由度和峰数二氧化碳的IR光谱http://bbs.elecfans.com电子技术论坛http://www.elecfans.com电子发烧友IR光谱得到的结构信息质量效应常见术语红外光谱的吸收强度红外吸收强度及其表示符号影响红外光谱吸收频率的因素各种化学键的红外吸收位置外在因素（测定条件）质量效应将（mX+1）/（mX+2）近似为1，则上式可简化为：
电子效应诱导效应、中介效应、和共轭效应诱导效应中介效应共轭效应:共轭效应使不饱和键的波数显著降低空间效应：环张力，空间位阻跨环共轭效应偶极场效应氢键效应振动耦合效应影响红外光谱吸收强度的因素振动中偶极矩的变化幅度越大，吸收强度越大红外光谱仪及样品制备技术色散型红外光谱仪傅立叶变换红外光谱仪干涉图FTIR光谱仪的优点红外光谱的测定方法http://bbs.elecfans.com电子技术论坛http://www.elecfans.com电子发烧友红外光谱的分区http://bbs.elecfans.com电子技术论坛http://www.elecfans.com电子发烧友各种有机化合物的红外光谱Whenyouanalyzethespectra,itiseasierifyoufollowaseriesofstepsinexaminingeachspectrum.

1.LookfirstforthecarbonylC::Oband.Lookforastrongbandat1820-1660cm-1.Thisbandisusuallythemostintenseabsorptionbandinaspectrum.Itwillhaveamediumwidth.Ifyouseethecarbonylband,lookforotherbandsassociatedwithfunctionalgroupsthatcontainthecarbonylbygoingtostep2.IfnoC::Obandispresent,checkforalcoholsandgotostep3.
2.IfaC::Oispresentyouwanttodetermineifitispartofanacid,anester,oranaldehydeorketone.Atthistimeyoumaynotbeabletodistinguishaldehydefromketoneandyouwillnotbeaskedtodoso.
ACIDLookforindicationsthatanO-Hisalsopresent.Ithasabroadabsorptionnear3300-2500cm-1.ThisactuallywilloverlaptheC-Hstretch.TherewillalsobeaC-Osinglebondbandnear1100-1300cm-1.Lookforthecarbonylbandnear1725-1700cm-1.
ESTERLookforC-Oabsorptionofmediumintensitynear1300-1000cm-1.TherewillbenoO-Hband.
ALDEHYDELookforaldehydetypeC-Habsorptionbands.ThesearetwoweakabsorptionstotherightoftheC-Hstretchnear2850cm-1and2750cm-1andarecausedbytheC-HbondthatispartoftheCHOaldehydefunctionalgroup.Lookforthecarbonylbandaround1740-1720cm-1.
KETONETheweakaldehydeCHabsorptionbandswillbeabsent.LookforthecarbonylCObandaround1725-1705cm-1.3.Ifnocarbonylbandappearsinthespectrum,lookforanalcoholO-Hband.
ALCOHOLLookforthebroadOHbandnear3600-3300cm-1andaC-Oabsorptionbandnear1300-1000cm-1.
4.IfnocarbonylbandsandnoO-Hban