円⼆⾊性分散計
Circular Dichroism spectrometer (CD)
基本仕様 / Specifications
日本分光株式会社（JASCO） J-1500
Ø 光源 / Light source : 150 W air-cooled Xenon lamp
Ø 検出器 / Detector : Head-on photomultiplier tube PMT
Ø 変調器 / Modulator : Photoelastic modulatorØ 測定波長範囲 / Measurement wavelength range : 163 - 950 nm

Ø バンド幅 / Spectral bandwidth : 0.01 - 16 nm
Ø スリット幅 / Slit width : 1 – 4000 µm
Ø レスポンス / Digital Integration Time (D.I.T.) : 0.1
msec - 30 sec
Ø スキャンスピード / Scan speed : 1 – 10000 nm/min
Ø CDフルスケール / CD full scale : ± 8000 mdegØ CD分解能 / CD resolution : 0.00001 mdeg
Ø LDフルスケール / LD full scale : ± 1 DOD
Ø LD分解能 / LD resolution : 0.000001 DOD

基本原理/ Mechanism

直線偏光（Linearly polarized light）

電磁波は、直行する電場と磁場中を進行方向に垂直に振動して伝わる横波です。自然界の光には、様々な向きに振動する光の成分が含まれています。これに対し、振動面がそろった光が直線偏光（左図上）、光の波の進行に伴い振動面が回転する偏光が円偏光です（左図下）。
Electromagnetic waves contain electrical and magnetic field components that oscillate perpendicularly
to the direction of propagation of the light beam. In natural light, these components vibrate in manydirections. On the other hand, in linearly polarized light, these vibrations are confined to a single plane (leftFig., upper). Another form of polarization is circularly polarized light, in which the vibration plane rotates as
the light beam propagates (left Fig., lower).
直線偏光（Linearly polarized light）

楕円偏光（Elliptically polarized light）

円偏光（Circularly polarized light）

直線偏光は、結晶軸や分子の向きが揃った光学素子（偏光子）に光を通過させることで得られます。円偏光は、直行する波のベクトル（電場ベクトル）の位相が1/4波長ずれたときに生じます。円偏光には左回り円偏光（El）と右回り円偏光（Er）とがあり、直線偏光は計算上、強度の等しいElとErの和と考えることができます（左図上）。強度が異なる場合のElとErの和が楕円偏光です（左図下）。
Linear polarization is obtained by passing light through an optical element (polarizer) in which thecrystal axes and the orientation of the molecules are aligned. Circular polarization occurs when the phaseof an orthogonal wave vector (electric field vector) deviates by 1/4 wavelength. Circularly polarized light
can be left-handed (El) and right-handed (Er), and linearly polarized light can be treated as the sum of El
and Er of equal intensity (left Fig., upper). When El and Er have different intensities, the resulting light isreferred to as elliptically polarized (left Fig., lower).

円二色性（circular dichroism: CD）は、光学活性物質の吸収波長領域において、左右円偏光の吸収の度合が異なる現象です。CD測定は、光学活性な試料に左右の円偏光を通すことで、それらの吸収の差を検出します。
左右の円偏光の吸収の差により透過光は楕円偏光となり、この不等吸収の現象を円二色性（CD）と呼び、楕円率θで表します（左図）。 この楕円率の波長依存性をプロットしたものを円二色性スペクトル（CD スペクトル）と呼びます。

楕円偏光（Elliptically polarized light）

Circular dichroism (CD) is a phenomenon in which the degree of absorption of left and right circularly
polarized light is different in the absorption wavelength range of optically active substances. CD
measurements detect these differences by passing left and right circularly polarized light through an
optically active sample. The transmitted light is then elliptically polarized, and this phenomenon is calledcircular dichroism (CD) and is expressed by the ellipticity θ (left Fig.). A plot of the wavelength
dependence of this ellipticity is called a circular dichroism spectrum (CD spectrum).

光学活性物質（Optically active substance）

出典：日本分光株式会社HP
https://www.jasco-global.com/principle/principles-of-cd-ord-1/-3

出典：日本分光株式会社HP
https://www.jasco.co.jp/jpn/technique/internet-seminar/cdord/cd4.html454040500O00

CH3CH3CD (mdeg)-500(+)-Camphor-1,000−1000

AbsAbsorbance

1.01

250
300
350
Wavelength (nm)400

H 3CCH3CH30.50.00
200
20000

abundant
TFE50%
添加a-helix
structure

O-20−20(-)-Camphor
250

300
350300
Wavelength (nm)Wavelength (nm)

400
400

Figure 1 CD (top) and absorption (bottom)
spectra of 0.4 w/v% camphor in ethanol.

-30
190

200
200220240220240
Wavelength [nm]Wavelength(nm)0-100-200−200

abundantpH2b-sheet
structure
塩酸中CD [mdeg]-1,500200

2020260260Figure 2 CD spectra of Concanavalin A inhydrochloric acid (pH = 2) aq. before (green line)
and after adding TFE with a ratio of 1:1 (blue line).

Abs

H 3C

Absorbance

1000
1,000q (mdeg)

CD (mdeg)

1,500

CD(mdeg)(mdeg)
CD

gabs

実用例/ Application Example

6.0x104.0x10-3
2.0x10-3
0.0-2.0x10-3-4.0x10-3-6.0x10-3
200200100

PNCs + right-handed silica helix

1.5
1.01
0.5
0.00200 300 400
400 500 600
600 700
200
Wavelength (nm)Wavelength(nm)

PNCs + left-handed silica helix

Figure 3 CD (top) and absorption (bottom) spectra ofperovskite nanocrystals (PNCs) grafted on silica helix
in the dried film.