Spectrophotometry

64問 • 1年前

問題一覧

Interaction of Radiation with a sample

Spectroscopy

The study of the molecular or atomic structure of a substance by observation of its interaction with electromagnetic radiation

Spectroscopy

Defined as method of analysis which deals with the measurement of spectra

Spectroscopy

for determining the amount of material in a sample

Quantitatively Spectroscopy

for identifying the chemical structure of a sample

Qualitatively Spectroscopy

the measurement of the absorption by chemical species of radiant energy of definite and narrow wavelengths approximating monochromatic radiation

Spectrophotometry

the absorption measurement is made in the visible region of the spectrum

Colorimetry

It is the term to define the complete system of energy propagated in waveform. Energy in this nature is referred to as radiant energy and appears in such different forms as sunlight, color, radiowaves, etc.

Electromagnetic spectrum

refers to the energy in the UV, Visible, and IR regions of the electromagnetic spectrum.

Radiant energy.

High energy sources produce the breaking of bonds

X-Ray, γ-Rays

Medium energy sources excite electrons

UV Spectroscopy, VISIBLE Spectroscopy

Low energy sources produce vibrations in chemical bonds

Infrared Energy

Very low energy sources produce rotation of the chemical bonds.

Microwaves, Radio waves

Electromagnetic radiation within a certain portion of the electromagnetic spectrum. The word usually refers to visible light, which is visible to the human eye and is responsible for the sense of sight.

Light

The length of a complete wave or cycle from a peak of the wave to the peak of the next

Wavelength

number of waves per centimeter

Wavenumber

a complete cycle that passes a given point per second

Frequency.

radiation of single wavelength

Monochromatic radiation

the absorption peaks that appear in this region are due to functional group

Group frequency region.

this region gives a spectrum of the molecule as a whole

Fingerprint region.

Absorbance and reflectance When a sample only absorbs light of a single wavelength the eye sees COMPLEMENTARY colors.

Visible spectroscopy.

If the material completely REFLECTS all light it appears

WHITE

If the material absorbs a constant fraction of the light across the spectrum it appears .

GREY

If the material completely ABSORBS all the light it appears

BLACK

functional group which absorbs radiant energy in the UV or VIS regions

Chromophore

The intensity of the transmitted radiant energy is a function of the concentration (T/F)

True

Radiative process an energy is lost by emission of radiation

Luminescence

energy is lost as heat

Collision deactivation.

Also called Flame photometry or flame emission spectroscopy

flame photometry

used to excite the analyte before measuring the emitted radiation

Flame spectroscopy

This technique is also used for the assay of other elements or metals such as potassium, sodium and calcium in blood and other biological samples.

Flame spectroscopy

For pharmaceuticals and biomolecules Use _________ absorbs light and emit fluorescent light

fluorophores

It is used in intensity vs wavelengths

Fluorometry

Very useful for qualitative analysis molecular structure analysis, complement to IR spectroscopy

Raman Spectroscopy

is similar to IR in that it is a vibrational spectroscopy technique

Raman Spectroscopy

same as incident light

Elastic scattering, Rayleigh

different wavelengths

Raman, Inelastic light

Energy difference between incident light and scattered light

Raman Spectroscopy

can be observed in the lower wavenumber or longer wavelength region and the opposite for the Antistoke

Strokes

an analytical chemistry technique used to measure the amount of turbidity or cloudiness in a solution caused by the presence of suspended insoluble particles.

Nephelometry

It is best suited and offers higher sensitivity for the analysis of small, suspended particles at low concentrations

Nephelometry

A technique is based on the measurement of the loss of intensity of transmitted light in an emulsion (or solution containing fine particles) due to the scattering effect of particles suspended in it.

Turbidimetry

The two possible used as light sources

Halogen, Xenon

a detector is placed opposite to the light source and at an angle relative to the incoming light beam

Turbidimeter

detector is placed at a 90 degree- angle

Nephelometer

Pharmaceutical industry, it is used to assess the solubility of drugs or compounds, for quantification of microbial growth, or cell count of microorganism

Nephelometry

used even though a compound ( or its colored derivative) to be analyzed absorbs in the UV region.

Colorimetric

Colorimeter is also called

filter photometer

Advantages of Colorimetry:

Simple instrument, Low cost, Use for qualitative and quantitative analysis

Colorimetry Works on the basis of Beer

Lambert’s law

Radiant energy absorbed is in the form of discrete parcels of energy known as

Photons, Quanta

• Associated with the overall motion of electrons around the nuclei

Electronic (UV)

• Associated with the motion of atoms within the molecule

Vibrational(IR)

• Associated with the overall rotation of the molecule

Rotational(Microwave)

• Associated with the motion of the molecule as a whole

Translational (notquantized)

When the transition back to the ground state is delayed it results to

phosphorescence

concentration of the solution containing the absorbing chemical species increases arithmetically

Beer law

The thickness of the solution containing the absorbing chemical species increases arithmetically

Bouguer’s law/Lambert

the thickness and concentration of the solution containing the absorbing chemical species

Beer – Lambert

Defined as the ratio of the intensity of light emerging from the solution (l) to that of the incident light entering (lo)

Transmittance

Also called optical density, absorbancy, extinction coefficient

Absorbance

absorbance (A) by the product of concentration

Absorptivity

dividing the absorbance (A) by the product of concentration of the solution,

Molar Absorptivity

The graph obtained when absorbance or any function of absorbance is plotted against wavelength.

Absorbance spectrum

Cell structure.

Quinn Karylle Fuentes · 28問 · 2年前

Cell structure.