Piv txwv ntawm Cov Lus Nug Sib Tham Infrared
Pendahuluuan
Infrared yog ib hom nthwv dej electromagnetic uas muaj qhov ntev ntev dua li lub teeb pom kev tab sis luv dua li cov nthwv dej xov tooj cua. Cov nthwv dej infrared muaj ntau yam kev siv, txij li thev naus laus zis thiab tshuaj mus rau kev sib txuas lus thiab kev ruaj ntseg. Hauv tsab xov xwm no, peb yuav tham txog ntau qhov piv txwv ntawm cov teeb meem cuam tshuam nrog infrared thiab lawv cov lus piav qhia kom nkag siab tob txog lub tswv yim no.
Kev Tshawb Fawb Infrared Yooj Yim
Infrared muaj qhov ntev ntawm 700 nanometers (nm) mus txog 1 millimeter (mm). Qhov ntev ntawm qhov ntev no tau raug tshawb pom los ntawm William Herschel hauv xyoo 1800 thaum ua kev sim los ntsuas qhov kub ntawm ntau yam xim hauv lub teeb spectrum. Nws pom tias cov cheeb tsam sab nraum lub spectrum liab, uas tib neeg lub qhov muag tsis pom, muaj qhov kub siab dua.
Infrared tau muab faib ua ntau pawg raws li nws qhov wavelength:
1. Nyob ze-Infrared (NIR): 700 nm – 1.4 µm
2. Nruab Nrab Infrared (Nruab Nrab-Infrared, MIR): 1.4 µm – 3 µm
3. Infrared deb (FIR): 3 µm – 1 hli
Cov khoom siv xws li lub koob yees duab infrared lossis thermography, cov chaw taws teeb tswj, thiab kev sib txuas lus fiber-optic siv cov thev naus laus zis infrared rau ntau yam lub hom phiaj. Lub teeb infrared kuj tseem siv tau los tshuaj xyuas cov khoom sib xyaw los ntawm infrared spectroscopy.
Cov Lus Nug Piv Txwv thiab Kev Sib Tham
Lo lus nug thib 1
Lo lus nug:
Lub chaw taws teeb TV siv lub teeb infrared los xa cov teeb liab mus rau lub TV. Yog tias lub wavelength ntawm lub teeb infrared siv yog 950 nm thiab qhov ceev ntawm lub teeb yog \(3 \times 10^8 \) m/s, qhov zaus ntawm lub teeb infrared yog dab tsi?
Kev Sib Tham:
Qhov zaus ntawm cov nthwv dej electromagnetic tuaj yeem suav los ntawm kev siv cov qauv yooj yim ntawm kev sib raug zoo ntawm wavelength (\(\lambda\)) thiab zaus (f):
\[ f = \frac{c}{\lambda} \]
nrog:
- \( f \) = zaus (Hz)
- \( c \) = qhov ceev ntawm lub teeb (\(3 \times 10^8 \) m/s)
- {\lambda} = wavelength (m)
Hauv lo lus nug no, qhov wavelength (\(\lambda\)) yog muab rau hauv nanometers (nm), yog li hloov mus rau meters (m) yog qhov tsim nyog:
\[ 950 \, nm = 950 \times 10^{-9} \, m \]
Tam sim no peb hloov cov nqi no rau hauv cov mis:
\[ f = \frac{3 \times 10^8 \, m/s}{950 \times 10^{-9} \, m} = 3.16 \times 10^{14} Hz \]
Yog li, qhov zaus ntawm nthwv dej infrared yog 3.16 lub sijhawm 10^{14} Hz.
Lo lus nug thib 2
Lo lus nug:
Lub koob yees duab infrared siv los ntes cov hluav taws xob kub los ntawm ib yam khoom. Lub koob yees duab muaj lub cuab yeej ntes tau qhov wavelengths ntawm 8 micrometers (µm) thiab 14 µm. Lub koob yees duab tuaj yeem ntes tau qhov zaus ntawm cov hluav taws xob ntau npaum li cas?
Kev Sib Tham:
Yuav kom xam tau qhov siab tshaj plaws thiab qhov tsawg kawg nkaus zaus, peb siv cov mis tib yam li hauv cov lus nug dhau los:
\[ f = \frac{c}{\lambda} \]
Ua ntej, hloov qhov wavelength ntawm micrometers (µm) mus rau meters (m):
\[ 8 \, µm = 8 \times 10^{-6} \, m \]
\[ 14 \, µm = 14 \times 10^{-6} \, m \]
Tam sim no xam qhov zaus siab tshaj plaws (\( f_{max} \)) thiab qhov zaus tsawg kawg nkaus (\( f_{min} \)):
\[ f_{max} = \frac{3 \times 10^8 \, m/s}{8 \times 10^{-6} \, m} = 3.75 \times 10^{13} Hz \]
\[ f_{min} = \frac{3 \times 10^8 \, m/s}{14 \times 10^{-6} \, m} = 2.14 \times 10^{13} Hz \]
Yog li, qhov zaus ntau uas lub koob yees duab infrared tuaj yeem ntes tau yog ≠ (2.14 lub sijhawm 10^{13}) Hz txog ≠ (3.75 lub sijhawm 10^{13}) Hz.
Lo lus nug thib 3
Lo lus nug:
Ib yam khoom tso tawm lub teeb infrared nrog qhov siab tshaj plaws ntawm qhov ntev ntawm 10 µm. Raws li Wien txoj cai hloov chaw, txiav txim siab qhov kub ntawm yam khoom. Siv Wien tus nqi tas mus li (\(b\)) ntawm \(2.898 \times 10^{-3} \, m \cdot K\).
Kev Sib Tham:
Txoj cai lij choj Wien displacement hais tias cov khoom ntawm qhov wavelength uas qhov siab tshaj plaws ntawm kev siv hluav taws xob tshwm sim (\(\lambda_{max}\)) thiab qhov kub thiab txias (T) ntawm cov khoom yog qhov tsis hloov pauv:
\[ \lambda_{max} \cdot T = b \]
nrog:
- \(\lambda_{max}\) = wavelength ntawm qhov siab tshaj plaws (m)
- T = qhov kub ntawm yam khoom (K)
– \(b\) = Wien tus nqi tas mus li (\(2.898 \times 10^{-3} \, m\cdot K\))
Nws paub tias \(\lambda_{max}\) yog 10 µm, uas yuav tsum tau hloov mus rau meters:
\[ 10 \, µm = 10 \times 10^{-6} \, m \]
Tam sim no hloov cov nqi no rau hauv tus qauv:
\[ 10 \times 10^{-6} \, m \cdot T = 2.898 \times 10^{-3} \, m \cdot K \]
Cov lus teb rau T yog:
\[ T = \frac{2.898 \times 10^{-3} \, m K}{10 \times 10^{-6} \, m} = 289.8 \, K \]
Yog li, qhov kub ntawm qhov khoom yog 289.8 K.
Lo lus nug thib 4
Lo lus nug:
Koj saib ib qho infrared spectrum ntawm ib qho organic chemical compound thiab pom ib qho absorbance peak ntawm 3 µm. Yog tias koj siv infrared spectroscopy, hom chemical bond twg yuav yog lub luag haujlwm rau qhov peak no?
Kev Sib Tham:
Kev siv infrared spectroscopy los ntawm qhov tseeb tias cov tshuaj molecule nqus cov infrared waves ntawm cov wavelengths tshwj xeeb uas sib raug rau cov zaus vibrational sab hauv ntawm cov molecule. Cov infrared wavelengths tshwj xeeb tuaj yeem cuam tshuam nrog cov hom kev sib txuas tshuaj tshwj xeeb:
- CH bonds hauv cov organic compounds feem ntau nqus tau ntawm qhov wavelengths ib ncig ntawm 3 µm.
- Cov OH bonds hauv cov cawv thiab cov carboxylic acids feem ntau nqus tau ntawm ib puag ncig 2.7-3.5 µm.
- NH bonds hauv amines feem ntau nqus tau ntawm ib puag ncig 3.1-3.3 µm.
Los ntawm cov ntaub ntawv muab, qhov absorbance peak ntawm 3 µm feem ntau yog vim CH kev co.
Yog li, tej zaum qhov uas yog lub luag haujlwm rau qhov absorbance peak ntawm 3 µm yog CH daim ntawv cog lus hauv cov organic tshuaj compound.
Xaus
Hauv tsab xov xwm no, peb tau tham txog ntau qhov teeb meem piv txwv thiab kev sib tham txog cov nthwv dej infrared. Los ntawm cov piv txwv no, peb tuaj yeem nkag siab ntxiv txog cov ntsiab lus yooj yim ntawm zaus, wavelength, thiab kub hauv cov ntsiab lus ntawm infrared radiation, nrog rau lawv cov ntawv thov hauv spectroscopy. Infrared yog ib feem tseem ceeb ntawm electromagnetic spectrum thiab muaj ntau daim ntawv thov hauv ntau qhov chaw, yog li kev kawm nws tuaj yeem muab cov kev nkag siab zoo rau cov xwm txheej ntuj thiab thev naus laus zis.
