Calcium-41 for Radiometric Dating

Why in news?

• Scientists have suggested using Calcium-41 for Radiometric Dating as an alternative to Carbon-14 for determining the age of fossilized bones and rocks.
• They have suggested a technique called Atom-Trap Trace Analysis (ATTA) as a solution, because ATTA is sensitive enough to spot Calcium-41, which is a rare isotope.

About Calcium-41:

• Calcium-41 is a rare long-lived radioisotope of calcium with a half-life of 99,400 years.
• Calcium-41 is produced in the Earth's crust when cosmic rays from space collide with calcium atoms in soil or rocks.
• This isotope has the potential to be employed in dating methods for objects that are older than what can be accurately determined using carbon-14 dating.

What is Atom-Trap Trace Analysis (ATTA)?

• It is based on laser manipulation and detection of neutral atoms.
• The sample is vaporized, and the atoms are laser-cooled and loaded into a light and magnetic field cage.
• By tuning the laser’s frequency, Calcium-41 atoms can be detected through electron transitions.
• Electron transition:
  • In an atom, an electron in one orbital can transition to the next if it’s given a specific amount of energy; then it jumps back by releasing that energy.
• The researchers reported being able to spot one calcium-41 atom in every 1016 calcium atoms with 12% precision in seawater.
• It is selective and avoids confusion with potassium-41 atoms.

Applications of ATTA:

• The successful application of a calcium isotope opens the possibility of extension to other metal isotopes.
• ATTA can be adapted to study other isotopes, such as argon-39, krypton-81, and krypton-85.
• In warmer climates, glaciers retreat and allow rock below to accumulate calcium-41. In colder climates, glaciers advance and block the calcium-41 from reaching the rock. This way, scientists hope to use ATTA to study how long some rock has been covered by ice.

About Radiometric Dating:

• Radiometric dating is a method used to determine the age of rocks, minerals, and fossils based on the decay of radioactive isotopes.
• It relies on the principle that certain isotopes of elements are unstable and spontaneously decay over time into more stable forms. The rate of decay is measured by the half-life, which is the time it takes for half of the parent isotope to decay into the daughter isotope.
• Different isotopes have different half-lives, which makes them useful for dating different time ranges.
  • For example, carbon-14 dating is effective for dating organic materials up to about 50,000 years old. When an organic entity is alive, its body keeps absorbing and losing carbon-14 atoms. When it dies, this process stops and the extant carbon-14 starts to decay away.
• Using the difference between the relative abundance of these atoms in the body and the number that should’ve been there, researchers can estimate when the entity died.

Limitations with Carbon-14:

• Carbon-14 is an unstable and weakly radioactive isotope of carbon. It has a half-life of 5,700 years and is used to estimate the age of carbon-based materials.
• Carbon dating using Carbon-14 is limited to objects up to 50,000 years old due to carbon-14's 5,700-year half-life.

PRACTICE QUESTION:

Radiocarbon dating is a widely used method to:

1. Measure the carbon footprint of firms and individuals

2. Establish the age of organic materials

3. Identify undesirable animal or plant materials in processed foods

Which of the statements given above is/are correct?

(a) 1 only

(b) 1 and 3 only

(c) 2 only

(d) 2 and 3 only

Answer