CALCIUM - 41 - SCI & TECH
News: New
technique welcomes calcium-41 to radiometric dating
What's in the news?
● One
important advancement was reported in Nature Physics i.e. calcium-41 can be
used in radiometric dating in March 2023.
Radio-carbon dating:
● Since
its invention in 1947, carbon dating has revolutionized many fields of science
by allowing scientists to estimate the age of an organic material based on how
much carbon-14 it contains.
● However,
carbon-14 has a half-life of 5,700 years,
so the technique cannot determine the age of objects older than around 50,000
years.
● 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 have been there, researchers can estimate when the
entity died.
Calcium-41 dating:
● Calcium-41
is a rare long-lived radio-isotope of
Calcium that has a half-life of 99,400 years.
● It
is produced when cosmic rays from space smash into calcium atoms in the soil,
and is found in the earth’s crust, opening the door to dating fossilized bones and rock.
Advantage:
● With
a half-life of 99,400 years, making it suitable for dating objects older than carbon-14 can handle.
Issues in Calcium-41 dating:
● Calcium-41
is rarer, occurring once in around 1015 calcium atoms.
Recently found methodology:
● A
technique called atom-trap trace
analysis (ATTA) has been developed to detect and analyze calcium-41 atoms.
● ATTA
involves vaporizing a sample and laser-cooling the atoms, then using laser
energy to detect the presence of calcium-41.
● Electron transition:
○ In
ATTA, a laser’s frequency is tuned such that it imparts the same energy as
required for an electron transition in calcium-41. The electrons absorb and
release this energy, revealing the presence of their atoms.
○ ATTA
also avoids potassium-41 atoms, which are similar to calcium-41 atoms but lack
the same electron transition.
Earth-science application of Calcium-41 dating:
● The
researchers are currently exploring an earth-science application.
○ 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.