ATOMIC SPECTROSCOPY

AAS is one of the analytical technique used for quantitative analysis by measuring the interaction of light with sample. Choose the correct principle of AAS.

• Non-excited atoms in the vapour state absorb radiation and are excited to higher states

• Medium absorbs radiation and transmitted radiation is measured

• An excited atoms return to ground state and emit radiation

AES is an analytical technique used for quantitative analysis for elements. Choose the correct principle of AES.

• Non-excited atoms in the vapour/gases state absorb radiation and are excited to higher states

• Medium absorbs radiation and transmitted radiation is measured

• An excited atoms return to ground state and emit radiation

The transformation of a liquid into spray of small droplets of aerosols is called ___________.

Answer explanation

The transformation of a liquid into a spray of small droplets is known as the atomization process. This process is essential in various applications, including medical nebulizers and spray technologies.

Select the process occuring during atomization

• desolvation

• nebulization

• combustion

• volatilization

Answer explanation

During atomization, processes like nebulization, desolvation, and volatilization occur, which involve converting a substance into small particles or vapor. These processes are essential for creating aerosols or fine sprays.

There are 2 types of burners in flame spectroscopy

• Spark burner

• Turbulent burner

• Continuum burner

• Premix burner

Answer explanation

In flame spectroscopy, the two main types of burners are the turbulent burner and the premix burner. The turbulent burner mixes fuel and oxidizer in a turbulent flow, while the premix burner ensures a uniform mixture before combustion.

Explain why source modulation is employed in AAS.

• to eliminate interference caused by emission of the

  radiated flame from analyte atoms and flame gas

  species.

• to tune the monochromator to a different spectral line for the element of interest so that there is no overlap.

• to distinguish between the component of radiation

  arising from the source and the component of

  radiation arising from the flame background.

Answer explanation

Source modulation in AAS is used to eliminate interference from the flame's radiation and to distinguish between the source's radiation and the flame background, ensuring accurate measurements of analyte concentrations.

Radiation source in AAS is a ___________ which provide narrow emission bands

• continuum source

• line source

Answer explanation

In Atomic Absorption Spectroscopy (AAS), a line source is preferred as it provides narrow emission bands, allowing for precise measurement of specific wavelengths. A continuum source, in contrast, emits a broad range of wavelengths.

Common radiation source for line source used in AAS

• Spark or arc ablation

• Hollow cathode lamp (HCL)

• Electrodeless discharge lamp (EDL)

Answer explanation

The common radiation sources for line sources in Atomic Absorption Spectroscopy (AAS) are the Hollow Cathode Lamp (HCL) and the Electrodeless Discharge Lamp (EDL), both of which provide specific wavelengths for element detection.

Interference: is the presence of substance that changes the signal from the analyte of interest when analytes concentration remain the same. List 3 interferences in AAS.

• Ionization interference

• Spectral interference

• Chemical interference

• Fundamental interference

Answer explanation

In AAS, interferences can affect the accuracy of measurements. Ionization interference occurs when the analyte ions are affected by other ions. Spectral interference arises from overlapping absorption lines, while chemical interference involves reactions that alter the analyte's state.

What is spectral interference?

• any physical process that effects the light intensity at the analytical wavelength

• some ions will be produced in hot flames

• alteration in analyte absorbance caused by chemical processes during atomization

Answer explanation

Spectral interference refers to any physical process that affects the light intensity at the analytical wavelength, which can lead to inaccuracies in measurements. This makes the first choice the correct answer.