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the incident beam. Excitation of the plasmon wave leads to a decreased intensity of

thereflected light. Thus, SPR produces a dip in the reflected light intensity at a specific

angle of reflection. The propagating surface plasmon wave enhances the amplitude of

the evanescent field wave, which extends into the sample region (Fig. 13.4b).

(b)

(c)

(a)

Dextran

Analyte

Gold

Sensorgram

I

II

Time

Angle

Resonance

signal

I II

Intensity

Polarised

light

Flow channel

Light-

source

Sensor chip with

gold film

Optical

detection

unit

Prism

I

II

Reflected

light

100 200 300 400 500 600

Time (s)

Resonance

signal (KRU)

Dissociation

Kinetics Regeneration

(^12) Association
14
16
18
Fig. 13.4The principles of surface plasmon resonance technology. (a) The sensor ‘chip’ surface. (b) The flow
channel. Insert: change in intensity of reflected light as a function of angle of incidence of the light beam, and
change in resonance signal as a function of time. (c) The sensorgram. (Reproduced by permission of GE Healthcare.)
528 Spectroscopic techniques: II Structure and interactions