Nws yog qhov yooj yim los piav qhia txog cov haujlwm txheeb ze ntawm cov resonances hauv NMR spectrum. Piv txwv li, lub ncov ntawm kev hloov pauv tshuaj, δ, ntawm 10 ppm yog hais tias yog downfield lossis deshielded nrog kev hwm rau lub ncov ntawm 5 ppm, lossis yog tias koj xav tau, lub ncov ntawm 5 ppm yog upfield lossis shielded nrog kev hwm rau lub ncov ntawm 10 ppm.
Deshielded txhais li cas hauv NMR?
Deshielding yog qhov ntxeev ntawm kev tiv thaiv. Thaum peb hais tias atom yog deshielded, peb txhais tau hais tias " Ib lub nucleus uas nws cov tshuaj hloov pauv tau nce vim yog tshem tawm ntawm electron ceev, sib nqus induction, lossis lwm yam teebmeem. "
Dab tsi yog qhov txawv ntawm downfield thiab upfield?
Cov ntsiab lus "upfield" thiab "downfield" piav qhia qhov chaw txheeb ze ntawm lub ncov. Upfield txhais tau tias mus rau sab xis. Downfield txhais tias rau sab laug.
hom protons tshwm sim li cas?
Yog li, lub davhlau ya nyob twg alkyne proton resonates upfield (~ 2.5 ppm) los ntawm alkene (~ 5.5 ppm) thiab aromatic protons(~ 7 ppm).
Dab tsi upfield thiab downfield qhia ntawm NMR spectrum?
Cov ntsiab lus upfield thiab downfield hais txog lub zog qis thiab siab ntawm cov teeb liab feem. Yog lawm, nws suab tsis meej pem vim koj xav kom lub downfield qhia ib cheeb tsam qis zog thiab upfield li zog dua.
