[{"data":1,"prerenderedAt":-1},["ShallowReactive",2],{"detail-sidebar-cat-1-en-105":3,"doc-seo-572735-105":53,"doc-detail-572735-en":120},{"code":4,"msg":5,"data":6},0,"success",[7,14,19,24,29,34,39,44,49],{"id":8,"doc_module":9,"doc_module_name":10,"category_name":11,"show_sort_weight":12,"slug":13},11,1,"Template","Presentations",90,"presentations",{"id":15,"doc_module":9,"doc_module_name":10,"category_name":16,"show_sort_weight":17,"slug":18},12,"Resumes",80,"resumes",{"id":20,"doc_module":9,"doc_module_name":10,"category_name":21,"show_sort_weight":22,"slug":23},14,"Invoices",70,"invoices",{"id":25,"doc_module":9,"doc_module_name":10,"category_name":26,"show_sort_weight":27,"slug":28},15,"Posters",60,"posters",{"id":30,"doc_module":9,"doc_module_name":10,"category_name":31,"show_sort_weight":32,"slug":33},16,"Social Media",50,"social-media",{"id":35,"doc_module":9,"doc_module_name":10,"category_name":36,"show_sort_weight":37,"slug":38},17,"Forms",40,"forms",{"id":40,"doc_module":9,"doc_module_name":10,"category_name":41,"show_sort_weight":42,"slug":43},18,"Letters",30,"letters",{"id":45,"doc_module":9,"doc_module_name":10,"category_name":46,"show_sort_weight":47,"slug":48},21,"Paper Templates",5,"papers-templates",{"id":50,"doc_module":9,"doc_module_name":10,"category_name":51,"show_sort_weight":4,"slug":52},158,"General","general-158",{"code":4,"msg":54,"data":55},"ok",{"site_id":56,"language":57,"slug":58,"title":59,"keywords":60,"description":61,"schema_data":62,"social_meta":113,"head_meta":115,"extra_data":117,"updated_unix":119},105,"en","ir-spectroscopy-infra-red-spectroscopy-notes","IR SPECTROSCOPY - Infra-red Spectroscopy Notes","","IR spectroscopy notes explain how to analyse an infra-red spectrum of a simple organic molecule to identify functional groups. The text describes how infrared radiation corresponds to vibrational bond motions, and why only molecules with changing polarity (polar molecules with dipole moments) absorb IR radiation. It covers reading an IR spectrum using baseline and absorption bands, interpreting key wavelength regions such as 400–4000 cm−1 and the fingerprint region, and distinguishing similar compounds using their spectra.",{"@graph":63,"@context":112},[64,80,95],{"@type":65,"itemListElement":66},"BreadcrumbList",[67,71,74,77],{"item":68,"name":69,"@type":70,"position":9},"https://docshare.wps.com","Home","ListItem",{"item":72,"name":10,"@type":70,"position":73},"https://docshare.wps.com/template/",2,{"item":75,"name":46,"@type":70,"position":76},"https://docshare.wps.com/template/paper-templates/",3,{"item":78,"name":59,"@type":70,"position":79},"https://docshare.wps.com/template/ir-spectroscopy-infra-red-spectroscopy-notes/572735/",4,{"url":78,"name":59,"@type":81,"author":82,"headline":59,"publisher":85,"fileFormat":88,"inLanguage":57,"description":61,"dateModified":89,"datePublished":89,"encodingFormat":88,"isAccessibleForFree":90,"interactionStatistic":91},"DigitalDocument",{"name":83,"@type":84},"วิน","Person",{"url":68,"name":86,"@type":87},"DocShare","Organization","application/pdf","2026-10-13",true,{"@type":92,"interactionType":93,"userInteractionCount":4},"InteractionCounter",{"@type":94},"ViewAction",{"@type":96,"mainEntity":97},"FAQPage",[98,104,108],{"name":99,"@type":100,"acceptedAnswer":101},"Why does infrared spectroscopy help identify functional groups?","Question",{"text":102,"@type":103},"Infrared radiation is absorbed at specific wavenumbers that correspond to vibrational bond motions in molecules. By analysing the spectrum’s absorbed frequencies, functional groups in organic molecules can be identified.","Answer",{"name":105,"@type":100,"acceptedAnswer":106},"Which molecules can absorb IR radiation?",{"text":107,"@type":103},"Only molecules that change their polarity as they vibrate can interact with infrared radiation. In practice, polar molecules with dipole moments absorb IR radiation.",{"name":109,"@type":100,"acceptedAnswer":110},"What is the fingerprint region in an IR spectrum?",{"text":111,"@type":103},"The region below about 1500 cm−1 is called the fingerprint region. It is characteristic of the molecule as a whole and can be compared with spectral databases to identify compounds.","https://schema.org",{"og:url":78,"og:type":114,"og:title":59,"og:site_name":86,"og:description":61},"article",{"robots":116,"canonical":78},"index,follow",{"doc_id":118,"site_id":56},572735,1791929066,{"code":4,"msg":5,"data":121},{"doc_id":118,"user_id":122,"nickname":83,"user_avatar":123,"doc_module":9,"category_id":45,"category_name":46,"doc_title":59,"doc_description":61,"doc_content":124,"file_id":125,"file_url":126,"file_type":127,"file_size":128,"view_count":4,"is_deleted":4,"is_public":9,"is_downloadable":9,"audit_status":9,"page_count":40,"language":129,"language_code":57,"site_id":56,"html_lang":57,"table_of_contents":130,"faqs":131,"seo_title":132,"seo_description":61,"update_tm":119,"read_time":133},2336475104736,"https://ap-avatar.wpscdn.com/avatar/22000c4c5e0e5b17e70?x-image-process=image/resize,m_fixed,w_180,h_180&k=1786591360781797222","| MEGA LECTURE · Free notes, practice tests and live classes |  [Back to megalecture.com](Back to megalecture.com) |  |  |\n| --- | --- | --- | --- |\n|  |  |  |  |\n\n277  \nIR SPECTROSCOPY  \na analyse an infra-red spectrum of a simple molecule to identify functional groups (seethe Data Booklet for functional groups required in the syllabus)  \nIR SPECTROSCOPY  \nCEDAR COLLEGE  \nIR SPECTROSCOPY  \nMEGA LECTURE ·  Free 1-on-1 demo class  Take a free test WhatsApp a tutor +92 336 7801123  \nScan: free demo class  \n278  \n\n| 22 Analytical techniques |  |\n| --- | --- |\n| Analytical techniques are important tools for investigating organic compounds. |  |\n| Learning outcomes\u003Cbr>Candidates should be able to: |  |\n| 22.2 Infra-red\u003Cbr>spectroscopy | a) analyse an infra-red spectrum of a simple molecule to identify functional groups (see the Data Booklet for functional groups required in the syllabus) |\n\nCEDAR COLLEGE  \nIR SPECTROSCOPY  \nMEGA LECTURE · Stuck on this topic?  Free 1-on-1 demo class  Take a free test WhatsApp a tutor +92 336 7801123  \n279  \n INFRA-RED (IR) SPECTROSCOPY   \nIR ABSORPTION  \nInfrared spectroscopy is used to identify functional groups in organic molecules. Most compounds absorb infrared radiation.  \nThe wavelengths ofthe radiation they absorb correspond to the natural frequencies at which vibrating bonds in the molecules bend and stretch.  \nHowever, it is only molecules that change their polarity as they vibrate that interact with infrared radiation.  \n2  \nCEDAR COLLEGE IR SPECTROSCOPY  \nMEGA LECTURE · Stuck on this topic?  Free 1-on-1 demo class  Take a free test WhatsApp a tutor +92 336 7801123  \n280  \nIR ABSORPTION  \nBonds vibrate in particular ways and absorb radiation at specific wavelengths. This means that it is possible to look at an infrared spectrum and identify functional groups.  \nAs a result, the infrared spectrum gives valuable clues to the presence of functional groups in organic molecules.  \nAn‘IR spectrum’ can be read to analyze the structure of an organic moleculemost importantly the functional groups present. These are analysed in an instrument called the spectrophotometer.  \nOnly molecules that are polar (and hence have dipole moments) can absorb IRradiation.  \n3  \nSKILL CHECK  \nWhich of these molecules will absorb IR radiation?  \nA. O2  \nB. HCN  \nC. H2S  \nD. N2  \nE. CCl4  \nF. CO2  \n4  \nCEDAR COLLEGE  \nIR SPECTROSCOPY  \nMEGA LECTURE · Stuck on this topic?  Free 1-on-1 demo class  Take a free test WhatsApp a tutor +92 336 7801123  \n281  \nIR ABSORPTION  \nThe major use of infrared spectroscopy is in determining the structures of organic compounds. In an infrared spectrometer, infrared radiation in the range 400–4000cm−1 is passed through a sample.  \nThe printout of the spectrum then shows which frequencies (wavenumbers) are absorbed.  \nInfrared spectra are always looked at with the baseline (representing 100% transmittance, i.e. zero absorbance) at the top.  \nThe troughs (usually called ‘bands’) thus represent wavenumbers at which radiation is absorbed.  \n5  \nIR SPECTRUM OF PROPANONE  \n[^c\\Zgeg^ci gZ\\^dc  \nLVkZcjbWZg$XbÄ&  \n6  \nCEDAR COLLEGE  \nIR SPECTROSCOPY  \nMEGA LECTURE · Stuck on this topic?  Free 1-on-1 demo class  Take a free test WhatsApp a tutor +92 336 7801123  \n282  \nIR SPECTRUM OF PROPANONE  \nThe infrared spectrum can be used to determine the bonds present in a molecule.  \nThus, in the region above 1500 cm−1 in the infrared spectrum of propanone there are two bands, corresponding to the C–H stretch and the C=O stretch.  \nThe region below 1500 cm−1 is called the ‘fingerprint region’ and is characteristic of the molecule as a whole. Comparison of the spectrum in the fingerprint region with spectra in databases of infrared spectra can be used to identify the molecule.  \nFor example, the infrared spectra of butanone and propanone can be distinguished using the fingerprint region. They both show very similar bands in the region above 1500cm−1 because they have the same functional group, but they h","cbCaigfPTovHhoPW","https://ap.wps.com/l/cbCaigfPTovHhoPW","pdf",13282462,"English","# 22.2 Infra-red spectroscopy\n## Learning outcomes\n## Infra-red (IR) absorption\n## Reading an IR spectrum\n## IR spectrum of propanone\n## Wavenumbers and bond identification","[{\"question\":\"Why does infrared spectroscopy help identify functional groups?\",\"answer\":\"Infrared radiation is absorbed at specific wavenumbers that correspond to vibrational bond motions in molecules. By analysing the spectrum’s absorbed frequencies, functional groups in organic molecules can be identified.\"},{\"question\":\"Which molecules can absorb IR radiation?\",\"answer\":\"Only molecules that change their polarity as they vibrate can interact with infrared radiation. In practice, polar molecules with dipole moments absorb IR radiation.\"},{\"question\":\"What is the fingerprint region in an IR spectrum?\",\"answer\":\"The region below about 1500 cm−1 is called the fingerprint region. It is characteristic of the molecule as a whole and can be compared with spectral databases to identify compounds.\"}]","IR SPECTROSCOPY - Infra-red Spectroscopy Notes | PDF",6]