PASCO SP-9268A User Manual

Instruction Manual
and Experiment Guide

for the PASCO scientific
Model SP-9268A

STUDENT

SPECTROMETER

012-02135F

10/03

Copyright © January 1991 $7.50

®

10101 Foothills Blvd. • P.O. Box 619011 • Roseville, CA 95678-9011 USA

Phone [phone] • FAX [phone] • email: [e-mail]

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ways to

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Model Name 012–0xxxxA

34

012-02135F Spectrometer

T ab le of Contents

Section Page

Equipment Return .............................................................................................ii

Introduction ......................................................................................................1

Equipment ........................................................................................................2

Equipment Setup...............................................................................................3

Measuring Angles of Diffraction ....................................................................... 4

Using the Diffraction Grating ............................................................................5

Using the Prism.................................................................................................6

Maintenance .....................................................................................................8

Appendix: Using the Gaussian Eyepiece ...........................................................9

Technical Support ..................................................................................... back cover

®

i

Spectrometer 012-02135F

Copyright, W arranty and Equipment Return

Please—Feel free to duplicate this manual
subject to the copyright restrictions below.

Copyright Notice

The PASCO scientific Model SP-9268A Student Spec­trometer manual is copyrighted and all rights reserved.
However, permission is granted to non-profit educational
institutions for reproduction of any part of this manual
providing the reproductions are used only for their
laboratories and are not sold for profit. Reproduction
under any other circumstances, without the written
consent of PASCO scientific, is prohibited.

Limited Warranty

PASCO scientific warrants this product to be free from
defects in materials and workmanship for a period of one
year from the date of shipment to the customer. PASCO
will repair or replace, at its option, any part of the
product which is deemed to be defective in material or
workmanship. This warranty does not cover damage to
the product caused by abuse or improper use. Determi­nation of whether a product failure is the result of a
manufacturing defect or improper use by the customer
shall be made solely by PASCO scientific. Responsibil­ity for the return of equipment for warranty repair
belongs to the customer. Equipment must be properly
packed to prevent damage and shipped postage or freight
prepaid. (Damage caused by improper packing of the
equipment for return shipment will not be covered by the
warranty.) Shipping costs for returning the equipment,
after repair, will be paid by PASCO scientific.

Equipment Return

Should this product have to be returned to PASCO
scientific, for whatever reason, notify PASCO scientific
by letter or phone BEFORE returning the product. Upon
notification, the return authorization and shipping
instructions will be promptly issued.

NOTE: NO EQUIPMENT WILL BE
ACCEPTED FOR RETURN WITHOUT
AN AUTHORIZATION.

When returning equipment for repair, the units must be
packed properly. Carriers will not accept responsibility
for damage caused by improper packing. To be certain
the unit will not be damaged in shipment, observe the
following rules:

1. The carton must be strong enough for the item
shipped.

2. Make certain there is at least two inches of packing
material between any point on the apparatus and the
inside walls of the carton.

3. Make certain that the packing material can not shift
in the box, or become compressed, thus letting the
instrument come in contact with the edge of the box.

Address: PASCO scientific

10101 Foothills Blvd.
P.O. Box 619011

Roseville, CA 95678-9011
Phone: [phone]
FAX: [phone]

ii

®

012-02135F Student Spectrometer

Introduction

In principle, a spectrometer is the simplest of scientific
instruments. Bend a beam of light with a prism or dif­fraction grating. If the beam is composed of more than
one color of light, a spectrum is formed, since the vari­ous colors are refracted or diffracted to different angles.
Carefully measure the angle to which each color of light
is bent. The result is a spectral "fingerprint," which car­ries a wealth of information about the substance from
which the light emanates.

In most cases, substances must be hot if they are to emit
light. But a spectrometer can also be used to investigate
cold substances. Pass white light, which contains all the
colors of the visible spectrum, through a cool gas. The
result is an absorption spectrum. All the colors of the vis­ible spectrum are seen, except for certain colors that are
absorbed by the gas.

The importance of the spectrometer as a scientific instru­ment is based on a simple but crucial fact. Light is emit­ted or absorbed when an electron changes its orbit within
an individual atom. Because of this, the spectrometer is a
powerful tool for investigating the structure of atoms. It's
also a powerful tool for determining which atoms are
present in a substance. Chemists use it to determine the
constituents of molecules, and astronomers use it to de­termine the constituents of stars that are millions of light
years away.

In its simplest form, a spectrometer is nothing more than
a prism and a protractor. However, because of the need
for very sensitive detection and precise measurement, a
real spectrometer is a bit more complicated. As shown in
Figure 1, a spectrometer consists of three basic compo­nents; a collimator, a diffracting element, and a tele­scope.

The light to be analyzed enters the collimator through a
narrow slit positioned at the focal point of the collimator
lens. The light leaving the collimator is therefore a thin,
parallel beam, which ensures that all the light from the
slit strikes the diffracting element at the same angle of
incidence. This is necessary if a sharp image is to be
formed.

The diffracting element bends the beam of light. If the
beam is composed of many different colors, each color is
diffracted to a different angle.

The telescope can be rotated to collect the diffracted
light at very precisely measured angles. With the tele­scope focused at infinity and positioned at an angle to
collect the light of a particular color, a precise image of
the collimator slit can be seen. For example, when the
telescope is at one angle of rotation, the viewer might
see a red image of the slit, at another angle a green im­age, and so on. By rotating the telescope, the slit images
corresponding to each constituent color can be viewed
and the angle of diffraction for each image can be mea­sured. If the characteristics of the diffracting element are
known, these measured angles can be used to determine
the wavelengths that are present in the light.

SOURCE

®

COLLIMATOR

SLIT

LIGHT

RED LIGHT

COLLIMATOR

PARALLEL BEAM

Figure 1 Spectrometer Diagram

DIFFRACTION GRATING

1

GREEN LIGHT

(OR PRISM)

TELESCOPE

ANGLE OF
DIFFRACTION

EYE PIECE