Chemistry - Radiometric Dating Flashcards
Radiometric Dating
This is the method of dating speciments by determination of relative proportions of particular radioactive isotopes in the sample.
How is C14 produced
Cosmic ray impacts knocking nitrogen protons loose
Cosmic Ray
Highly energetic atomic nuclei travelling through space at speed approaching that of light.
What happens to C14 when it is produced?
It distributes along the carbon cycle, decaying by electron emission.
Why are geiger counters inefficient?
Inhibition by other radioactive particles.
What are the three ways C14 is measured?
Gas Proportional Counting
Liquid Scintillation Counting
Accelerator Mass Spectrometry
Gas Proportional Counting
Proportional counters are gaseos ionization detectors that measure particles of ionizing radiations.
Liquid Scintilattion Counting
This measures beta-meitting and alpha-emitting isotopes, liquidifying sample carbon to benzene, then measuring radioacitvity in a scintillation counter.
How do scintillation counters work?
Detecting/measuring ionizing radiation by using incident radiation excitation.
Scintillator
A material with the property of luminescense, scintillating, when excited by ionizing radiation.
What happens when a scintillator detects incident radiation?
Generates protons where a photodetector converts light into an electrical signal.
Photodetector
This detects/responds to incident light by sing photon electrical effects.
Accelerator Mass Spectrometry
This is a mass spectrometer that accelerates ions to extrdinarily high kinetic energies before mass analysis.
Mass Spectrometers
Measure mass-to-charge ratio before mass analysis
What ages does radiocarbon dating produce?
Radiocarbon years, which must be callibrated to calendar years.
What is the most common form of radiometric callibration?
Tree trings
What is an example of tree dating?
Maunder minium, sun spots dramatically decreased, tree trings showed ratio of C14/C increased.
Why does C14/C ratio increase with increased dsolar radiation?
Ion increase and heliospheric magnetic field
Heliospheric magnetic field
Component of the solar magnetic field dragged out from the solar corona by the solar wind flow to fill the solar systems
What is a potential cause of the holocene?
Earths magnetic field change deflecting sun rays.
How are magnetic fields measured?
Magnetic chronology
How was carbon dating used as proof for TC shutodwn cause of YD?
C14/C increased bt 5% during first 200 years, then drifted back down during remaining 1000 years
How can past radiacne measured?
Solar irradiance is tied in C14 increase
How did C14 related to hydrogen bombinb ing 50s/60s
Released neutrons collided with atmospheric nitrogen doubled C14 ratios
Beta Decay
This is the emission of electrons or positrongs, or process of electron capture.
Half life
This is the rate at which it takes half the material of an atom to decay.
What happens after 10 half lives of c14
57,300 years amount is about 0.1%, too hard to detect
How does C14 relate to age of an object?
Older artifacts have less C14 than younger ones.
