6: Spectroscopic Methods
- Page ID
- 526593
\( \newcommand{\vecs}[1]{\overset { \scriptstyle \rightharpoonup} {\mathbf{#1}} } \)
\( \newcommand{\vecd}[1]{\overset{-\!-\!\rightharpoonup}{\vphantom{a}\smash {#1}}} \)
\( \newcommand{\id}{\mathrm{id}}\) \( \newcommand{\Span}{\mathrm{span}}\)
( \newcommand{\kernel}{\mathrm{null}\,}\) \( \newcommand{\range}{\mathrm{range}\,}\)
\( \newcommand{\RealPart}{\mathrm{Re}}\) \( \newcommand{\ImaginaryPart}{\mathrm{Im}}\)
\( \newcommand{\Argument}{\mathrm{Arg}}\) \( \newcommand{\norm}[1]{\| #1 \|}\)
\( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\)
\( \newcommand{\Span}{\mathrm{span}}\)
\( \newcommand{\id}{\mathrm{id}}\)
\( \newcommand{\Span}{\mathrm{span}}\)
\( \newcommand{\kernel}{\mathrm{null}\,}\)
\( \newcommand{\range}{\mathrm{range}\,}\)
\( \newcommand{\RealPart}{\mathrm{Re}}\)
\( \newcommand{\ImaginaryPart}{\mathrm{Im}}\)
\( \newcommand{\Argument}{\mathrm{Arg}}\)
\( \newcommand{\norm}[1]{\| #1 \|}\)
\( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\)
\( \newcommand{\Span}{\mathrm{span}}\) \( \newcommand{\AA}{\unicode[.8,0]{x212B}}\)
\( \newcommand{\vectorA}[1]{\vec{#1}} % arrow\)
\( \newcommand{\vectorAt}[1]{\vec{\text{#1}}} % arrow\)
\( \newcommand{\vectorB}[1]{\overset { \scriptstyle \rightharpoonup} {\mathbf{#1}} } \)
\( \newcommand{\vectorC}[1]{\textbf{#1}} \)
\( \newcommand{\vectorD}[1]{\overrightarrow{#1}} \)
\( \newcommand{\vectorDt}[1]{\overrightarrow{\text{#1}}} \)
\( \newcommand{\vectE}[1]{\overset{-\!-\!\rightharpoonup}{\vphantom{a}\smash{\mathbf {#1}}}} \)
\( \newcommand{\vecs}[1]{\overset { \scriptstyle \rightharpoonup} {\mathbf{#1}} } \)
\( \newcommand{\vecd}[1]{\overset{-\!-\!\rightharpoonup}{\vphantom{a}\smash {#1}}} \)
\(\newcommand{\avec}{\mathbf a}\) \(\newcommand{\bvec}{\mathbf b}\) \(\newcommand{\cvec}{\mathbf c}\) \(\newcommand{\dvec}{\mathbf d}\) \(\newcommand{\dtil}{\widetilde{\mathbf d}}\) \(\newcommand{\evec}{\mathbf e}\) \(\newcommand{\fvec}{\mathbf f}\) \(\newcommand{\nvec}{\mathbf n}\) \(\newcommand{\pvec}{\mathbf p}\) \(\newcommand{\qvec}{\mathbf q}\) \(\newcommand{\svec}{\mathbf s}\) \(\newcommand{\tvec}{\mathbf t}\) \(\newcommand{\uvec}{\mathbf u}\) \(\newcommand{\vvec}{\mathbf v}\) \(\newcommand{\wvec}{\mathbf w}\) \(\newcommand{\xvec}{\mathbf x}\) \(\newcommand{\yvec}{\mathbf y}\) \(\newcommand{\zvec}{\mathbf z}\) \(\newcommand{\rvec}{\mathbf r}\) \(\newcommand{\mvec}{\mathbf m}\) \(\newcommand{\zerovec}{\mathbf 0}\) \(\newcommand{\onevec}{\mathbf 1}\) \(\newcommand{\real}{\mathbb R}\) \(\newcommand{\twovec}[2]{\left[\begin{array}{r}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\ctwovec}[2]{\left[\begin{array}{c}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\threevec}[3]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\cthreevec}[3]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\fourvec}[4]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\cfourvec}[4]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\fivevec}[5]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\cfivevec}[5]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\mattwo}[4]{\left[\begin{array}{rr}#1 \amp #2 \\ #3 \amp #4 \\ \end{array}\right]}\) \(\newcommand{\laspan}[1]{\text{Span}\{#1\}}\) \(\newcommand{\bcal}{\cal B}\) \(\newcommand{\ccal}{\cal C}\) \(\newcommand{\scal}{\cal S}\) \(\newcommand{\wcal}{\cal W}\) \(\newcommand{\ecal}{\cal E}\) \(\newcommand{\coords}[2]{\left\{#1\right\}_{#2}}\) \(\newcommand{\gray}[1]{\color{gray}{#1}}\) \(\newcommand{\lgray}[1]{\color{lightgray}{#1}}\) \(\newcommand{\rank}{\operatorname{rank}}\) \(\newcommand{\row}{\text{Row}}\) \(\newcommand{\col}{\text{Col}}\) \(\renewcommand{\row}{\text{Row}}\) \(\newcommand{\nul}{\text{Nul}}\) \(\newcommand{\var}{\text{Var}}\) \(\newcommand{\corr}{\text{corr}}\) \(\newcommand{\len}[1]{\left|#1\right|}\) \(\newcommand{\bbar}{\overline{\bvec}}\) \(\newcommand{\bhat}{\widehat{\bvec}}\) \(\newcommand{\bperp}{\bvec^\perp}\) \(\newcommand{\xhat}{\widehat{\xvec}}\) \(\newcommand{\vhat}{\widehat{\vvec}}\) \(\newcommand{\uhat}{\widehat{\uvec}}\) \(\newcommand{\what}{\widehat{\wvec}}\) \(\newcommand{\Sighat}{\widehat{\Sigma}}\) \(\newcommand{\lt}{<}\) \(\newcommand{\gt}{>}\) \(\newcommand{\amp}{&}\) \(\definecolor{fillinmathshade}{gray}{0.9}\)An early example of a colorimetric analysis is Nessler’s method for ammonia, which was introduced in 1856. Nessler found that adding an alkaline solution of HgI2 and KI to a dilute solution of ammonia produced a yellow-to-reddish brown colloid, in which the colloid’s color depended on the concentration of ammonia. By visually comparing the color of a sample to the colors of a series of standards, Nessler was able to determine the concentration of ammonia. Colorimetry, in which a sample absorbs visible light, is one example of a spectroscopic method of analysis. At the end of the nineteenth century, spectroscopy was limited to the absorption, emission, and scattering of visible, ultraviolet, and infrared electromagnetic radiation. Since then, spectroscopy has expanded to include other forms of electromagnetic radiation—such as X-rays, microwaves, and radio waves—and other energetic particles—such as electrons and ions.
- 6.1: Overview of Spectroscopy
- This chapter explores the interaction of electromagnetic radiation with matter, particularly in the context of spectroscopy. It covers the principles of spectroscopy using ultraviolet, visible, and infrared radiation. The chapter explains the wave and particle nature of electromagnetic radiation, highlighting its fundamental properties and explaining how matter absorbs or emits photons.
- 6.2: Spectrometer
- A spectrometer is any instrument used to view and analyze a range (or a spectrum) of a given characteristic for a substance (e.g., a range of mass-to-charge values as in mass spectrometry) , or a range of wavelengths as in absorption spectrometry like nuclear magnetic radiation spectroscopy or infrared spectroscopy). A spectrophotometer is a spectrometer that only measures the intensity of electromagnetic radiation (light) and is distinct from other spectrometers such as mass spectrometers.
- 6.3: Spectroscopy Based on Absorption
- The page explains the principles and applications of absorption spectroscopy. It describes how electromagnetic radiation passes through a sample, and selective absorption at certain wavelengths leads to attenuation, essential for identifying various molecular and atomic transitions. The page covers the requirements for an analyte's absorption, mechanisms involved, differences in infrared and UV/Vis spectra, and factors influencing spectral characteristics.
- 6.4: Lasers
- LASER is an acronym for Light Amplification by Stimulated Emission of Radiation. Laser is a type of light source which has the unique characteristics of directionality, brightness, and monochromaticity. The goal of this module is to explain how a laser operates (stimulated or spontaneous emission), describe important components, and give some examples of types of lasers and their applications.
- 6.5: UV/Vis and IR Spectroscopy
- The page discusses the evolution of color matching in spectroscopy, detailing the transition from Nessler's original method to modern photoelectric and infrared methods in the 1930s and 1940s. It then describes different instrument designs for molecular absorption spectroscopy, including filter photometers, single-beam and double-beam spectrophotometers, and diode array spectrometers, highlighting their features and limitations.
- 6.6: Signals and Noise
- When we try to calibrate an analytical method or to optimize an analytical system, our ability to do so successfully is limited by the uncertainty, or noise, in our measurements and by background signals that interfere with our ability to measure the signal of interest to us. In this chapter we will consider how we characterize noise, example of sources of noise, and ways to clean up our data by decreasing the contribution of noise to our measurements and by correcting for the presence of backgr
- 6.7: Emission Spectroscopy
- This page discusses the concept of an analyte in an excited state and the processes of relaxation to its lower energy state. It elaborates on how excess energy is released in various ways, including as heat through vibrational relaxation, through photochemical reactions, or as a photon via electromagnetic radiation.
- 6.8: Photoluminescent Spectroscopy
- This page provides an in-depth explanation of photoluminescence, dividing it into two categories: fluorescence and phosphorescence. It describes the processes, mechanisms, and factors influencing both types, including radiative and non-radiative deactivation pathways. The page discusses the technological advancements in fluorescence and phosphorescence spectroscopy, related instrumentation, and depicts their quantitative applications for analyzing inorganic and organic analytes.
- 6.9: Analytical Chemiluminescence
- The aim of the book is to give a comprehensive account of the chemiluminescence subject suitable for students, research workers, professional analytical chemists and life scientists. The chemistry of each reagent that has been used in chemiluminescence is explained and the techniques for increasing the magnitude of the emitted signal are discussed. Further sections describe the different instrumental methods that have been used and examine the sort of work that has been carried out with them.
- 6.12: Applications of Infrared Spectrometry
- Infrared spectroscopy finds wide use for both qualitative and quantitative analysis. Our organization of IR applications follows that traditionally used by others by dividing the broad range of infrared radiation into three distinct units: the near-IR, the mid-IR, and the far-IR. Note that the near in near-IR means that it is nearest to the visible range of light. Of these, the most important in terms of the breadth of applications is the mid-IR.
- 6.14: Problems
- The document appears to be focused on various analytical chemistry problems involving spectrophotometry, colorimetry, and molecular absorption techniques in different contexts such as determining concentrations of elements or compounds in different scenarios like solutions, beverages, and solid matrices. The problems cover applications of Beer???s Law, stoichiometry of complex formation, and effects of instrumental limitations.
- 6.15: Additional Resources
- The page provides a comprehensive overview of various experiments in spectroscopy targeted at students, organized into categories such as UV/Vis spectroscopy, IR spectroscopy, atomic absorption and emission, fluorescence and phosphorescence, and signal averaging.
- 6.16: Chapter Summary and Key Terms
- The chapter covers spectrophotometric techniques based on the absorption, emission, or scattering of electromagnetic radiation. It explains how molecules and atoms absorb radiation, causing changes in energy states, and measures such as Beer???s law are used to relate absorbance to concentration. The chapter describes atomic absorption and emission methods, as well as scattering techniques like turbidimetry and nephelometry. Key terms related to spectroscopy methods and processes are included.