English for Specialized Chemistry 3- Group 7

LOGO

SPECTROSCOPYGROUP 7

ENGLISH FOR

SPECIALIZED CHEMISTRY 3

LOGOMembers of group 7

Dinh Thi Minh Nhat

Nguyen Thi Doi

Nguyen Van Sang

Nguyen Linh Tam

Ha Cuong Tuyen

Nguyen Thanh Huy

Nguyen Thi Thu Sen

Nguyen Thanh Luan

Tran Thi Thu Thao

1

2

3

4

5

6

7

8

9

LOGOContents

Introduction to spectroscopy1

Absortion spectrum2

Emission spectrum3

Ultraviolet – visible and infrared spectrophotometry4

LOGOIntroduction to spectroscopy

What is spectrophotometry ?

Spectrophotometry is the quantitative

measurement of the reflection or transmission

properties of a material as a function of

wavelength.


major

minor

limited


One example Nessler


Alkaline solution


Equal volumes of the sample and standards


application


At the and of 19th

century


transferof energy

Interaction of radiation


Emission


Asborption

LOGOAbsortion spectrum


Atoms and molecules absorb light, the incoming energy excites a quantized

structure to a higher energy level.

The type excitation depends on the wavelength of the light.

LOGO Absortion spectrum


E total = E electronic + E vibration + E rotation

Electrons are promoted

to higher orbital by

ultraviolet or visible light.

Vibrations are excited by

infrared light.

Rotations are excited by

microwaves

LOGOAbsortion spectrumAn absortion spectrum is the

absortion of light as a function of

wavelength.

The spectrum of an atom or

molecule depends on its energy

level structure, and absortion

spectra are useful for identifying of

compounds.

LOGOAbsortion spectrumMeasuring the concentration

of an absortion species in a

sample is accomplished by

applying the Beer-Lambert

Law

Absorbance = A

(or Optical Density

= OD)

It measures the intensity of light passing through a sample (I)

compares it to the intensity of light before it passes through the sample (I0)

LOGOEmission spectrum

Emission spectrum of hydrogen

Emission – liminescence

Emission spectrum of iron

The relationship among the wavelength and the

energy E are: E =

where c is the speed of light and h is Planck's

Constant.


Atomic-opical emission

For atoms excited by a high temperature energy

source this light emission is commonly called

atomic or optical


Atomic fluorescence

For atoms excited with light it is

called atomic fluorescence


Fluorescence- phosphorescence

Eneration of luminescence through excitation of a molecule which is formally

divided into two categories, fluorescence and phosphorescence.

If the transition is between states of the same spin, it will call fluorescence.

If the transition is between states of different spin, it will call phosphorescence.

LOGOEmission spectrum Applies

At low concentrations the emission intensity will generally be proportional to the

concentration of the emission

The emission spectrum can be used to determine the composition of a material

LOGOUltraviolet – visible and infrared spectrophotometry


Ranges radiation

760 – 400 nm1000 – 760 nm

400 – 100 nm


sunlight

Visible light that you see

vis

IR

uv

Source of lights radiation

Infrared radiation that can be felt as heat

Ultraviolet radiation that can’t be seen or left

LOGOUltraviolet – visible spectrophotometry

- The most common spectrophotometers

are used in the UV and visible regions of

the spectrum.

- They take readings in the region of

every 5–20 nanometers along the

visible region.


Ultraviolet Lights


Visible Lights

LOGOInfrared spectrophotometry

Thermocouples for infrared radiation

Absorbed infrared radiation causes

rotational changes in molecules

IR

Infrared radiation was discovered

1800

LOGOInfrared spectrophotometry

LOGOReferences

[1]. Le Thi Thanh Huong, English for specialized chemistry, Ho

Chi Minh city University of Industry, 2012.

LOGO

www.themegallery.com

English for Specialized Chemistry 3- Group 7

Documents

Transcript of English for Specialized Chemistry 3- Group 7