Molecular Emission Spectroscopy and Raman Spectroscopy

A comprehensive set of 300 flashcards covering key concepts, definitions, and applications related to molecular emission spectroscopy and Raman spectroscopy.

Molecular Emission Spectroscopy

An analytical technique that studies the light emitted by molecules when they are excited to higher energy states.

Fluorescence Spectrophotometry

A method of fluorescence detection based on the intensity of emitted light after excitation.

Right-Angle Geometry

Excitation light is collected at a right angle (90°) to reduce the amount of incident light entering the detector.

Front-Face Geometry

Excitation light strikes the sample at a shallow angle, and emission is collected directly from the front surface.

Transmitting Geometry

Excitation light enters the sample straight through (0°) and emission is collected directly opposite (180°).

Concentration Effects

A phenomenon where high sample concentration leads to reabsorption of emitted light, decreasing fluorescence intensity.

Quenching by Heavy Atoms

The reduction of fluorescence intensity due to the presence of heavy atoms that dissipate excited-state energy.

Chemical Complex Formation

The phenomenon where the binding or association with other molecules can alter fluorescence properties.

Temperature Effects

The influence of temperature on fluorescence intensity, with higher temperatures typically reducing fluorescence.

Stokes Shift

The difference in energy/wavelength between absorbed and emitted light, usually resulting in emitted light at a longer wavelength.

Fluorescent Molecules

Molecules that emit light after absorbing energy, particularly those with rigid structures like aromatic hydrocarbons.

Non-Fluorescent Molecules

Molecules that fail to emit light because absorbed energy is lost as vibrational relaxation.

Excitation Source in Fluorescence

The light source used for exciting the sample, commonly a quartz halogen or xenon lamp.

Emission Monochromator

A device that analyzes emitted light and separates true fluorescence from scattered excitation light.

Photomultiplier Tube (PMT)

A highly sensitive detector used in fluorescence spectrophotometry to convert emitted light into an electrical signal.

Rayleigh Scatter

Elastic scattering of light by solvent molecules that does not change the light's energy.

Tyndall Scatter

Scattering caused by larger particles or colloids in a solution, which can enhance background noise.

Raman Scattering

Inelastic scattering of light where a photon exchanges energy with molecular vibrations, providing molecular fingerprints.

Raman Effect

The change in wavelength of light as it interacts with molecular vibrations, leading to Stokes and anti-Stokes scattering.

Protection from Rayleigh Scattering

Filters or monochromators are used to block Rayleigh-scattered light in Raman spectroscopy.

Fluorescence Spectrum

The emission spectrum of fluorescent light showing the wavelengths of light emitted from a sample.

Analytical Technique

A method used to study the properties and behaviors of chemical substances.

Vibrational Modes

Types of molecular motion like bending, stretching, and twisting that can affect emission properties.

Absorption Maximum (λmax)

The wavelength at which a molecule absorbs the maximum amount of light.

Excitation Wavelength Selector

A component that selects the specific wavelength of light used to excite a sample in fluorescence measurements.

Excitation Monochromator

Device used to select a particular wavelength of light from the excitation source.

Collisional Quenching

Dissipation of excited state energy due to frequent molecular collisions that lead to non-radiative decay.

Inner Filter Effect

A decrease in fluorescence intensity due to the absorption of emitted light by the sample itself.

Vibrational Relaxation

The process by which excess energy from an excited molecule is lost through molecular vibrations.

Chemiluminescence

The emission of light as a result of a chemical reaction, without requiring an external light source.

Fluorescence Microscopy

A technique that uses fluorescence to study samples, particularly biological specimens.

Detector in Fluorescence Spectroscopy

Device that measures the emitted fluorescence and converts it to an electrical signal.

Quantum Yield (Φ)

A measure of the efficiency of fluorescence emission, ranging from 0 (non-fluorescent) to 1 (highly fluorescent).

Characteristic Emission Lines

Unique wavelengths of light emitted by atoms or molecules, used in spectroscopy for identification.

Emission of Light

The process of a molecule releasing energy in the form of light as it returns to a lower energy state.

Metastable State

An excited state of an electron where it can remain trapped before returning to the ground state.

Radiative Decay

The process by which an excited electron releases energy in the form of light.

Laser in Raman Spectroscopy

A coherent light source used to induce Raman scattering in samples.

Vibrational Energy Levels

Quantized states of energy associated with the vibrations of a molecule.

Heavy Atom Effect

The reduction of fluorescence due to the presence of heavy atoms which quench emitted light.

Spectroscopic Fingerprint

Unique spectral features of a substance that help identify it, akin to a molecular fingerprint.

Sample Holder

Container that securely holds the sample in place during fluorescence measurements.

Fluorescence Quantum Yield (Φ)

The ratio of the number of photons emitted to the number of photons absorbed.

Rayleigh and Raman Scatter Comparison

Rayleigh scatter is elastic and wavelength-independent, while Raman scatter is inelastic and wavelength-dependent.

Excited Electronic States

Higher energy states of electrons resulting from the absorption of light.

Rigidity in Molecules

Structural stability in a molecule that affects its ability to fluoresce.

Polarizability in Raman Spectroscopy

The ability of a molecule to distribute its electron cloud under the influence of an electromagnetic field.

Weaker Scattering in Solvents

Raman scattering is weaker than Rayleigh and Tyndall scattering, but still detectable.

Chemical Complexes

Structures formed when molecules interact and bind together, affecting fluorescence.

Minor Quantum Mechanical Effects

Effects that arise due to the underlying quantum nature of molecular interactions.

Fluorescence Emission Characteristics

Properties of emitted light including wavelength and intensity that provide information about the sample.

Optical Filters

Devices used to selectively transmit or block specific wavelengths of light.

Broadband Spectrum in Atomic Emission

A wide range of emitted wavelengths due to multiple electronic and vibrational transitions.

Intraparticle Effects

Interactions between particles that affect the overall fluorescence of a material.

Spectroscopy Techniques

Various methods of analyzing samples based on interactions between light and matter.

Water as a Solvent

A common solvent in spectroscopy due to its transparency in many light wavelengths.

Fluorescent Pollutants

Contaminants that can fluoresce, which may be analyzed using fluorescence spectroscopy.

Cuvette

A small, usually rectangular container used to hold liquid samples for optical measurement.

Broadband Light Sources

Sources emitting a wide range of wavelengths for exciting samples in fluorescence studies.

Dilution in Spectroscopy

The process of reducing the concentration of a sample to avoid interference during measurement.

Excitation Light Conditions

The specific light conditions under which a sample is excited and measured in spectroscopic studies.

Detection Limits in Fluorescence

The lowest concentration of a substance that can be reliably detected using fluorescence techniques.

Quantum Mechanical Principles

Fundamental theories governing the behavior of particles at the atomic and subatomic scales.

Deactivation Pathways

Routes through which excited states can return to ground states without emitting light.

Internal Conversion

A process where an excited molecule loses energy non-radiatively, often through vibrations.

Detection Geometry

Alignment of detectors in relation to the excitation source to optimize measurement conditions.

Emission Spectra Overlap

When emission spectra of different species interfere with one another in a sample.

Chemical Reactions Inducing Fluorescence

Processes in which specific interactions lead to observable fluorescence.

Spectrum Resolution

The ability to distinguish between different wavelengths of light in a spectrum.

Intensity of Emitted Light

How bright or strong the emitted light appears during fluorescence measurement.

Fluorescence vs. Phosphorescence

Fluorescence is rapid emission, while phosphorescence involves delayed emission due to energy trapping.

Inelastic Scattering

The change in energy of a photon after interacting with a molecule, relevant in Raman scattering.

Quantitative Analysis in Fluorescence

The process of measuring specific concentrations of substances using fluorescence techniques.

Interference Factors in Fluorescence

Factors like solvent interactions and temperature that can affect fluorescence measurements.

Emitted Light Wavelengths

The specific wavelengths of light that are emitted from a molecule during fluorescence.

Altering Fluorescence Properties

Changes in fluorescence behavior due to molecular structure or external conditions.

Molecular Strain Effects

Deformation or changes in molecular structure affecting the energy of fluorescent emissions.

Electromagnetic Waves in Spectroscopy

Light waves utilized in various forms of spectroscopic analysis to measure substance properties.

Colloidal Solutions

Mixtures where fine particles are dispersed within a liquid, affecting light scattering.

Resonance Fluorescence

Fluorescence that occurs when the excitation light frequency matches a molecular transition.

Sample Dilution Effects

Impact of reducing sample concentration on the accuracy and reliability of fluorescence measurements.

Binding Affinity Measurements

Usage of fluorescence to study how molecules interact and bind with each other.

Monochromatic Light Usage

The use of a single wavelength of light for precise excitation in spectroscopic techniques.

Energy Transfer Mechanisms

Processes through which energy can be transferred from one molecule to another.

Atomic vs. Molecular Emission

Differences in emission characteristics between single atoms and complex molecules.

Sample Transparency

The degree to which a sample allows light to pass through, affecting spectroscopic results.

Quantum Mechanical Behavior in Molecules

The principles that describe the behavior and properties of molecules on a quantum level.

Emission Peak Characteristics

Parameters that define the shape and position of peaks in an emission spectrum.

Intermolecular Interactions

Forces between molecules that can influence emission characteristics in fluorescence.

Application of Raman in Formulations

Using Raman spectroscopy to analyze drug formulations and their behavior.

Resolving Spectra in Raman Techniques

The capability to distinguish between various spectral lines when using Raman methods.

Chemical Structure Identification

Determining the arrangement of atoms within a molecule based on spectroscopic data.

Combinatorial Anthracene Studies

Investigation of fluorophores and their behavior using anthracene as a model.

Spectroscopic Equipment Calibration

Establishing proper settings for equipment to ensure accurate spectroscopic measurements.

Non-Radiative Energy Loss

Processes leading to energy dissipation without the emission of light.

Quantitative Spectroscopy Applications

Use of spectroscopic methods to quantify the concentration of substances in samples.

Metal Ion Effects on Fluorescence

Influence of metal ions on fluorescence intensity and behavior of molecules.

Chirality in Molecules

The property of a molecule that makes it non-superimposable on its mirror image, affecting fluorescence.

Energy State Transitions

Changes between different energy levels in a molecule leading to absorption or emission.

Detection Sensitivity in Spectroscopy

The ability of a technique to detect low concentrations of a substance.