A) Single-Beam

Total Page：16

File Type：pdf, Size：1020Kb

Lecture 2 Spectrophotometer Spectrophotometry is the basis for many of the instruments used in clinical chemistry. The primary reasons for this are ease of measurement, satisfactory accuracy and precision, and the suitability of spectrophotometric techniques to use in automated instruments. Spectrophotometer measures light absorption by a liquid substance at various wavelengths. The Components of unknown material can be determined, or the concentration of a number of known substances can be measured. Types of Spectrophotometer Ultraviolet (UV) Spectrophotometers. Uses ultraviolet light of wave lengths from 200 nm to 350 nm. light) of wave lengths from 350 nm to 700 nm. Spectrophotometer Block Diagram a) Single-beam b) Double-beam Most common Spectrophotometer 1. Photodiode 2. Connection wire 3. Lamp 4. Filter/Detector 5. On/Off switch and zero transmission adjustment knob 6. Wavelength selector/Readout 7. Sample chamber 8. Transmittance/absorbance control 9. Absorbance/Transmittance scale 1. Light Sources Tungsten lamp: Vis. near IR (320 nm~2500 nm) Deuterium arc lamp: UV (200~400 nm) Uses a tungsten filament and anode placed on opposite sides of a nickel box structure designed to produce the best output spectrum. Unlike tungsten lamps, the filament is not the source of light in deuterium lamps. Instead an arc is created from the filament to the anode. The arc created excites the molecular deuterium contained within the bulb to a higher energy state. The deuterium then emits light as it transitions back to its initial state Its continuous spectrum is only from 180 nm to 370 nm. Light Intensity of Tungsten and Deuterium lamps A problem with tungsten lamps is that, during operation, the tungsten progressively vaporizes from the filaments and condenses on the glass envelope. This coating, which is generally uneven, alters the spectral characteristics of the lamp and can cause errors in determinations. Gas-discharge lamp (Vis & UV) Generate light by sending an electrical discharge through an ionized gas. This light can be anything between IR, visible or UV radiation Typically, these lamps use nobble gases such as argon, neon, Helium, xenon, or a mixture of these gasses. Many lamps are also filled with additional gases like sodium and mercury. Each gas, depending on its atomic structure emits certain wavelengths which translates in different colors of the lamp. Gas-discharge lamps offer long life and high efficiency. Laser High power Very good for studying reactions Narrow line width Coherence Can fine-tune the desired wavelength (but choice of wavelength is limited) .

Copy Link

Recommended publications

UV-VIS Nomenclature and Units
IN804 Info Note 804: UV-VIS Nomenclature and Units Ultraviolet-visible spectroscopy or ultraviolet-visible spectrophotometry (UV/VIS) involves the spectroscopy of photons in the UV-visible region. It uses light in the visible and adjacent near ultraviolet (UV) and near infrared (NIR) ranges. In this region of the electromagnetic spectrum, molecules undergo electronic transitions. This technique is complementary to fluorescence spectroscopy, in that fluorescence deals with transitions from the excited state to the ground state, while absorption measures transitions from the ground state to the excited state. UV/VIS is based on absorbance. In spectroscopy, the absorbance A is defined as: (1) where I is the intensity of light at a specified wavelength λ that has passed through a sample (transmitted light intensity) and I is the intensity of the light before it enters the sample or 0 incident light intensity. Absorbance measurements are often carried out in analytical chemistry, since the absorbance of a sample is proportional to the thickness of the sample and the concentration of the absorbing species in the sample, in contrast to the transmittance I / I of a 0 s ample, which varies exponentially with thickness and concentration. The Beer-Lambert law is used for concentration determination. The term absorption refers to the physical process of absorbing light, while absorbance refers to the mathematical quantity. Also, absorbance does not always measure absorption: if a given sample is, for example, a dispersion, part of the incident light will in fact be scattered by the dispersed particles, and not really absorbed. Absorbance only contemplates the ratio of transmitted light over incident light, not the mechanism by which light intensity decreases.
[Show full text]
UV-Vis) Absorption Vs
授課教師: Professor 吳逸謨教授 Warning: Copyrighted by textbook publisher. Do not use outside class. Principles of Instrumental Analysis Section III – Molecular Spectroscopy Chapter 13 Introduction to Ultraviolet-Visible Absorption Spectrometry + Chapter 14 Applications of Ultraviolet-Visible Absorption Spectrometry Reference: p. 423, Visible and UV spectra, in “Organic Chemistry” textbook – Solomons, 3rd Ed] 1 Molecular Spectroscopy Ultraviolet–visible (UV-Vis) absorption vs. fluorescence Spectroscopy Ultraviolet–visible spectroscopy or ultraviolet-visible spectrophotometry (UV-Vis or UV/Vis) refers to absorption spectroscopy or reflectance spectroscopy in the ultraviolet-visible spectral region. This means it uses light in the visible and adjacent (near-UV and near- infrared [NIR]) ranges. The absorption or reflectance in the visible range directly affects the perceived color of the chemicals involved. In this region of the electromagnetic spectrum, molecules undergo electronic transitions. Fluorescence spectroscopy is based on molecular emission: The “UV-Vis” technique is complementary to fluorescence spectroscopy, in that fluorescence deals with transitions from the excited state to the ground state, while UV-Vis absorption measures transitions from the ground state to the excited state.[1] 2 (2007/3) UV-Vis Spec 儀器 -實驗課 3 FIGURE 6-3 Regions of the electromagnetic spectrum. (For UV-Vis, λ = 100~500 nm, 500~1000 nm) 4 Ch6 An Introduction to Spectrometric Methods P.135 Apendix: Chap. 7E - Radiation Transducers p. 191 Read the texts in Chap. 7 7E-2 Photon Transducers for optical spectroscopy – Barrier-Layer Photovoltaic Cells – Vacuum Phototubes – Photomultiplier tubes (PMT), picture on p. 195 – Silicon Photodiodes (Fig. 7-32) [semiconductor type] [A silicon photodiode transducer consists of a reverse- biased p-n junction.] (The latter two types of transducers are more commonly used in UV-Vis.) – We will discuss more details later.
[Show full text]
Replacing the AMOR with the Minidoas in the Ammonia Monitoring Network in the Netherlands
Atmos. Meas. Tech., 10, 4099–4120, 2017 https://doi.org/10.5194/amt-10-4099-2017 © Author(s) 2017. This work is distributed under the Creative Commons Attribution 3.0 License. Replacing the AMOR with the miniDOAS in the ammonia monitoring network in the Netherlands Augustinus J. C. Berkhout1, Daan P. J. Swart1, Hester Volten1, Lou F. L. Gast1, Marty Haaima1, Hans Verboom1,a, Guus Stefess1, Theo Hafkenscheid1, and Ronald Hoogerbrugge1 1National Institute for Public Health and the Environment (RIVM), P.O. Box 1, 3720 BA Bilthoven, the Netherlands anow at: Royal Netherlands Meteorological Institute (KNMI), P.O. Box 201, 3730 AE De Bilt, the Netherlands Correspondence to: A. J. C. Berkhout ([email protected]) Received: 16 October 2016 – Discussion started: 3 March 2017 Revised: 31 August 2017 – Accepted: 16 September 2017 – Published: 2 November 2017 Abstract. In this paper we present the continued develop- nitrogen oxides or sulfur dioxide. These aerosols contribute ment of the miniDOAS, an active differential optical ab- to the total burden of particulate matter and may have public sorption spectroscopy (DOAS) instrument used to measure health effects (Fischer et al., 2015). When deposited on na- ammonia concentrations in ambient air. The miniDOAS has ture areas, ammonia causes acidiﬁcation and eutrophication, been adapted for use in the Dutch National Air Quality Mon- leading to a loss of biodiversity. Intensive animal husbandry itoring Network. The miniDOAS replaces the life-expired leads to high ammonia emissions in the Netherlands. Hence, continuous-ﬂow denuder ammonia monitor (AMOR). From it is of great importance to have a correct understanding of September 2014 to December 2015, both instruments the sources and sinks of ammonia in the Netherlands and of measured in parallel before the change from AMOR to the processes that determine ammonia emissions to the air, miniDOAS was made.
[Show full text]
Fundamentals of Modern UV-Visible Spectroscopy
Fundamentals of modern UV-visible spectroscopy Primer Tony Owen Copyright Agilent Technologies 2000 All rights reserved. Reproduction, adaption, or translation without prior written permission is prohibited, except as allowed under the copyright laws. The information contained in this publication is subject to change without notice. Printed in Germany 06/00 Publication number 5980-1397E Preface Preface In 1988 we published a primer entitled “The Diode-Array Advantage in UV/Visible Spectroscopy”. At the time, although diode-array spectrophotometers had been on the market since 1979, their characteristics and their advantages compared with conventional scanning spectrophotometers were not well-understood. We sought to rectify the situation. The primer was very well-received, and many thousands of copies have been distributed. Much has changed in the years since the first primer, and we felt this was an appropriate time to produce a new primer. Computers are used increasingly to evaluate data; Good Laboratory Practice has grown in importance; and a new generation of diode-array spectrophotometers is characterized by much improved performance. With this primer, our objective is to review all aspects of UV-visible spectroscopy that play a role in obtaining the best results. Microprocessor and/or computer control has taken much of the drudgery out of data processing and has improved productivity. As instrument manufacturers, we would like to believe that analytical instruments are now easier to operate. Despite these advances, a good knowledge of the basics of UV-visible spectroscopy, of the instrumental limitations, and of the pitfalls of sample handling and sample chemistry remains essential for good results.
[Show full text]
Chapter 2 Experimental Methodology
CHAPTER 2 Chapter 2 Experimental Methodology 2.1 Introduction 2.2 Synthesis of nanomaterials. 2.2.1 DC arc plasma reactor setup for material processing 2.2.2 Microwave processing of materials 2.2.2.1 Microwave Induced Plasma processing System setup 2.2.2.2 Multimode Microwave setup 2.3 Analytical techniques for characterization nanophase powders 2.3.1 X- ray diffraction study 2.3.2 X-Ray photoelectron spectroscopy 2.3.3 Surface area measurement (BET method) 2.3.4 Electron Microscopy (SEM and TEM) 2.3.4.1 Scanning electron microscopy (SEM) 2.3.4.2 Transmission Electron Microscopy (TEM) 2.3.5 DTA&TGA 2.3.6 Vibrating sample magnetometer (VSM) 2.3.7 Ultraviolet visible spectroscopy (UV/vis) 2.3.8 Raman spectroscopy 2.3.9 Photoluminescence spectroscopy 2.4 Conclusion 2.5 References. 36 CHAPTER 2 Chapter 2 Experimental Methodology 2.1 Introduction This chapter provides the detailed description of the experimental setups for (i) DC arc plasma (reactor) & (ii) microwave processing systems used for the synthesis of nanophase materials and (iii) other analytical-measuring methods such as of X-ray diffraction, X-ray photoelectron spectroscopy, surface area using BET method, scanning and transmission electron microscopy (SEM / TEM), UV-Visible absorption spectroscopy, thermal analysis (DTA / TGA), vibrating sample magnetometer (VSM), Raman and Photoluminescence spectroscopy. 2.2 Synthesis of nanomaterials 2.2.1 DC arc plasma reactor setup for material processing The experimental DC arc plasma setup used for the synthesis of various nano materials is as shown in figure 2.1 (a). The plasma reactor consisted of a multi port stainless steel chamber (12 inch in diameter) with a multiple gas inlet facility providing various mixtures of gases, which can be incorporated as plasma forming gas.
[Show full text]
Replacing the AMOR by the Minidoas in the Ammonia Monitoring Network in the Netherlands A.J.C
Atmos. Meas. Tech. Discuss., doi:10.5194/amt-2016-348, 2017 Manuscript under review for journal Atmos. Meas. Tech. Discussion started: 3 March 2017 c Author(s) 2017. CC-BY 3.0 License. Replacing the AMOR by the miniDOAS in the ammonia monitoring network in the Netherlands A.J.C. (Stijn) Berkhout1, Daan P.J. Swart1, Hester Volten1, Lou F.L. Gast1, Marty Haaima1, Hans Verboom1*, Guus Stefess1, Theo Hafkenscheid1, Ronald Hoogerbrugge1 5 1National Institute for Public Health and the Environment (RIVM), P.O. Box 1, 3720 BA Bilthoven, the Netherlands *Now at Royal Netherlands Meteorological Institute (KNMI), P.O. Box 201, 3730 AE De Bilt, the Netherlands Correspondence to: A.J.C. Berkhout ([email protected]) Abstract. In this paper we present the continued development of the miniDOAS, an active differential optical absorption spectroscopy (DOAS) instrument to measure ammonia concentrations in ambient air. The miniDOAS has been adapted for 10 use in the Dutch National Air Quality Monitoring Network. The miniDOAS replaces the life-expired continuous-flow denuder ammonia monitor (AMOR). From September 2014 to December 2015, both instruments measured in parallel before the change from AMOR to miniDOAS was made. The instruments were deployed on six monitoring stations throughout the Netherlands. We report on the results of this intercomparison. Both instruments show a good uptime of ca. 90%, adequate for an automatic monitoring network. Although both instruments 15 produce minute values of ammonia concentrations, a direct comparison on short timescales such as minutes or hours does not give meaningful results, because the AMOR response to changing ammonia concentrations is slow.
[Show full text]
Hollow Cathode Lamps
Hollow Cathode Lamps Cathodeon The Ultimate Source MADAtec Srl www.madatec.com Tel. +39-0236542401 Cathodeon HOLLOW CATHODE LAMPS CONTENTS 1 Hollow cathode lamps 5 See through hollow cathode lamps 6 Single element lamps 15 Multi element lamps 22 Getting the best from your hollow cathode lamps 24 Hollow cathode lamps supply 25 Periodic table 1 Hollow Cathode Lamps Cathodeon CATHODEON HOLLOW CATHODE DISCHARGE LAMPS Fig 2 Cathodeon Ltd with over 60 years’ experience in vacuum/gas Internal construction and piece parts HOLLOW electronic devices is the worlds leading specialist in spectral source technology. Now Europe’s undisputed leader in the manufacture of hollow cathode lamps having been at the CATHODE heart of their design and development since the early years of atomic absorption analysis in the 1960’s. LAMPS Cathodeon hollow cathode lamps are fitted as original equipment by many of the worlds foremost atomic absorption instrument manufacturers, and as replacements by discerning users the world over. The Cathodeon hollow cathode lamp programme includes 70 single element and the widest range of proven multi element combinations in standard 11/2” (37mm), and 2” (50mm) diameters designed to fit directly into Perkin Elmer AA APPLICATIONS equipment. Where appropriate these lamps are available These components combined create a mechanically consistent with data coded bases permitting the instrument to automatically Hollow cathode lamps are and robust lamp with the beam of light focused through the identify the lamp element. In addition a range of lamps centre of the window and free from spurious discharge problems. specifically designed for use with Smith Hieftje background gas discharge devices in correction systems is available.
[Show full text]
UV-Vis Spectroscopy
Ultraviolet and visible spectroscopy Dr. Ahmad Najjar Philadelphia University Faculty of Pharmacy Department of Pharmaceutical Sciences 1st semester, 2020/2021 Spectrophotometry Spectroscopy is a general term referring to the interactions (mainly absorption and emission) of various types of electromagnetic radiation with matter. Spectrophotometry is a method to measure how much a chemical substance absorbs or emits light by measuring the intensity of light (electromagnetic radiation). It refers to the use of light (electromagnetic radiation) to measure chemical concentrations. Electromagnetic spectrum refers to the full range of all frequencies of electromagnetic radiation, which is refers to the waves of the electromagnetic field, propagating through space carrying electromagnetic energy. Electromagnetic radiation Electromagnetic radiation (EMR) has been described in terms of a stream of photons that travel in a wave-like pattern. Each photon contains a certain amount of energy, and all electromagnetic radiations consists of these photons. All electromagnetic radiations travels in a straight line at the Crest Crest speed of light (3 x 108 m/s). The only difference between the various types of electromagnetic radiations is the amount of energy found in the photons. Electromagnetic radiations are described by several terms Trough such as wavelength, frequency, wave number and energy. λ wavelength (units : m,cm, μm, nm) ν 1/λ ν frequency (units of cycles/sec, sec1, Hertz c ν λ ν /ν c ν wavenumber (number of waves per cm; unit : cm1) Energy (E) h ν h h c ν λ 8 1 velocityof light in vacuum c ν λ 3.00 10 m.s h is planck's constant 6.62x10-34 J.s Electromagnetic radiation Crest Crest Electromagnetic wave is also characterized by several fundamental properties, including its velocity, amplitude, phase angle, polarization, and direction of propagation.
[Show full text]
Deuterium Lamp Layout NEWEST
Deuterium Lamps Cathodeon The Ultimate Source Cathodeon DEUTERIUM LAMPS CONTENTS 1 Introduction 2 Internal structure 4 Envelopes 5 Window materials 7 Lamps in operation 8 Selection criteria 14 Fibre-coupled deuterium lamp 15 Industrial deuterium lamps 16 VUV lamps 17 Analytical VUV lamps 18 Power supply for deuterium lamps 19 Pulsed deuterium lamps 20 Power supply for pulsed deuterium lamps 21 High power deuterium lamp 22 Power supply and housing for high power deuterium lamp 23 Modulated deuterium lamp system 24 Useful notes 1 Deuterium Lamps Cathodeon CATHODEON DEUTERIUM LAMPS INTERNAL CONSTRUCTION Cathodeon Ltd, with almost 60 years experience in vacuum/gas INTRODUCTION filled electronic devices, is the world leading specialist in Fig 2a Standard deuterium lamp spectral source technology. Involved in the design and Anode Compartment manufacture of deuterium lamps since the earliest days of Arc Aperture instrumental spectroscopy, the company was ideally placed to Anode meet the challenges imposed on deuterium lamp performance Box by the low noise and drift requirements of HPLC during its Dimple Structure rapid growth in the early 1970’s. This long experience and Filament Shield expertise in deuterium arc lamp manufacture has resulted Cathode in an unrivalled range of products to meet many scientific Front Aperture needs. Continuing improvement to production techniques, Cathode quality control standards and test specifications ensure Dimple / Centre Plate Compartment that Cathodeon deuterium lamps remain the first choice Compartment of instrument manufacturers and discerning scientists APPLICATIONS throughout the world. For users wishing to combine light from another source with Deuterium arc lamps are the beam from the deuterium lamp, a “see through” facility is Fig 1 Spectral distribution offered.
[Show full text]
Glass Filters As a Standard Reference Material for Spectrophotometry Selection, Preparation, Certification, and Use of SRM 930 and SRM 1930
— NATL INST. OF STAND & TECH R.I.C. NISI PUBLICATIONS A 111 DM 2A7D2S 5 NIST SPECIAL PUBLICATION 260-116 U.S. DEPARTMENT OF COMMERCE/Technology Administration National Institute of Standards and Technology Standard Reference Materials: Glass Filters as a Standard Reference Material for Spectrophotometry Selection, Preparation, Certification, and Use of SRM 930 and SRM 1930 R. Mavrodineanu, R. W. Burke, J. R. Baldwin, M. V. Smith, QC J. D. Messman, J. C. Travis, and J. C. Colbert 100 . U57 NO. 260-1 16 1994 The National Institute of Standards and Technology was established in 1988 by Congress to "assist industry in the development of technology . needed to improve product quality, to modernize manufacturing processes, to ensure product reliability . and to facilitate rapid commercialization . of products based on new scientific discoveries." NIST, originally founded as the National Bureau of Standards in 1901, works to strengthen U.S. industry's competitiveness; advance science and engineering; and improve public health, safety, and the environment. One of the agency's basic functions is to develop, maintain, and retain custody of the national standards of measurement, and provide the means and methods for comparing standards used in science, engineering, manufacturing, commerce, industry, and education with the standards adopted or recognized by the Federal Government. As an agency of the U.S. Commerce Department's Technology Administration, NIST conducts basic and applied research in the physical sciences and engineering and performs related services. The Institute does generic and precompetitive work on new and advanced technologies. NIST's research facilities are located at Gaithersburg, MD 20899, and at Boulder, CO 80303.
[Show full text]
Chemical Analysis
Chemical Analysis Modern Instrumentation Methods and Techniques Second Edition Francis Rouessac and Annick Rouessac University of Le Mans, France Translated by Francis and Annick Rouessac and Steve Brooks Chemical Analysis Second Edition Chemical Analysis Modern Instrumentation Methods and Techniques Second Edition Francis Rouessac and Annick Rouessac University of Le Mans, France Translated by Francis and Annick Rouessac and Steve Brooks English language translation copyright © 2007 by John Wiley & Sons Ltd, The Atrium, Southern Gate, Chichester, West Sussex PO19 8SQ, England Telephone (+44) 1243 779777 Email (for orders and customer service enquiries): [email protected] Visit our Home Page on www.wiley.com Translated into English by Francis and Annick Rouessac and Steve Brooks First Published in French © 1992 Masson 2nd Edition © 1994 Masson 3rd Edition © 1997 Masson 4th Edition © 1998 Dunod 5th Edition © 2000 Dunod 6th Edition © 2004 Dunod This work has been published with the help of the French Ministère de la Culture-Centre National du Livre All Rights Reserved. No part of this publication may be reproduced, stored in a retrieval system or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, scanning or otherwise, except under the terms of the Copyright, Designs and Patents Act 1988 or under the terms of a licence issued by the Copyright Licensing Agency Ltd, 90 Tottenham Court Road, London W1T 4LP, UK, without the permission in writing of the Publisher. Requests to the Publisher should be addressed to the Permissions Department, John Wiley & Sons Ltd, The Atrium, Southern Gate, Chichester, West Sussex PO19 8SQ, England, or emailed to [email protected], or faxed to (+44) 1243 770571.
[Show full text]
Radiometric Calibrations of Portable Sources in the Vacuum Ultraviolet
Volume 93, Number 1, January-February 1988 Journal of Research of the National Bureau of Standards Radiometric Calibrationsof PortableSources in the Vacuum Ultraviolet Volume 93 Number 1 January-February 1988 Jules Z. Kiose, J. Mervin The radiometric calibration program their uncertainties. Finally, the calibra- Bridges, and William R. Ott carried out by the vacuum ultraviolet tion services are delineated in an ap- radiometry group in the Atomic and pendix. National Bureau of Standards Plasma Radiation Division of the Na- Gaithersburg, MD 20899 tional Bureau of Standards is presented in brief. Descriptions are given of the Key words: arc (argCn); arc (blackbody); primary standards, which are the hydro- arc (hydrogen); irradiance; lamp (deu- gen arc and the blackbody line arc, and terium); radiance; radiometry; Standards the secondary standards, which are the (radiometric); ultraviolet; vacuum ultra- argon mini- and maxi-arcs and the deu- violet. terium arc lamp. The calibrationmeth- ods involving both spectral radiance and irradiance are then discussed along with Accepted: October 2, 1987 1. Introduction desired wavelength. In this case the most direct procedure is to employ a standard source. The The vacuum ultraviolet (VUV) region of the source to be investigated as well as the standard spectrum has become important in several areas of source are set up in turn so that radiation from each research and development. These include space- source passes through the same monochromator based astronomy and astrophysics, thermonuclear and optical elements. The calibration is performed fusion research, ultraviolet laser development, and essentially by a direct substitution of the standard general atomic physics research. Applications of source for the one to be calibrated.
[Show full text]