2. History and background
• Based on Einstein’s 1917 stimulated emission principle
• Two soviet scientists, Nikolay Basov and Alexander
Prokhorov came up with the idea in 1952
• In 1953, the first ammonia maser was developed by Townes,
Gordon and Zeiger at Columbia University.
• Norman Ramsey created the first laboratory hydrogen maser
in 1960. His design is still being used today
• Discovery of laser (optical maser) was followed in December
of 1958
• Natural masers in space have been discovered since 1965
4. Microwave
• Masers are just like lasers except that the radiation they emit is in the
microwave part of the electromagnetic spectrum.
• This light has a longer wavelength and less energy than the visual light
emitted by lasers.
5. Amplified
• Radiation from a maser or laser is much more intense than
radiation from other light sources.
• The amplified light from lasers can be strong enough to cut
through granite.
• The amplified light from Masers can be strong enough to be seen
from billions of light years away.
• To radio telescopes, masers look like very small, very bright dots.
Just as if someone was shining a laser-pointer at you from across
the room.
6. Stimulated Emission
• Masers are so powerful because they emit from regions with a population
inversion
• These regions are unstable and can lead to the stimulated emission of large
quantities of radiation.
7. Population Inversion
• Every electron in a system has a certain amount of
energy.
• Population Inversion occurs when most of the
electrons are in the higher energy state.
Normal population Inverted population
8. Stimulated Emission
• one of the electrons randomly jumps to the lower energy level. When it
does, it emits a photon with an energy equal to the energy difference
between the two levels.
9. Radiation
• Light bulbs emit electromagnetic radiation in a most
disorganized way.
• MASERS emit radiation much more orderly. Because they were
produced by stimulated emission.
• All the photons are monochromatic, in phase, similarly
polarized, and travel in the same direction.
10. First Maser
• The first maser was an ammonia-
beam maser (1954)
• The two energy levels used in the
ammonia maser are vibrational states
of the ammonia molecule
• The hydrogen atoms can be
considered to rotate
• The nitrogen atom oscillates between
two positions, above and below the
plane of the hydrogen atoms
N
H
H
H
N
H
H
H
11. Monochromatic
Light is a wave with frequency, wavelength and energy. The
“light” emitted by a MASER is of one frequency, wavelength
and energy. Color is related to frequency and so the light is
said to be monochromatic. (Mono = one, chromatic = color)
monochromatic not monochromatic
12. In phase
• Light is a wave and has a
wavelength.
• If two waves begin at the
same point, they are in
phase. Added together,
their amplitude increases.
• When two waves begin at
different points, they are out
of phase. If they are added
together, their amplitude
decreases.
13. Polarization
Waves can be
polarized in four
different ways. All
the microwaves
emitted by a maser are
polarized in the same
way.
Right handed
left handed
Vertical
Horizontal
14. Masers in Space
Several different types of molecular masers have
been discovered in space. They produce radiation
using chemicals including:
Hydroxyl (OH)Formaldehyde (H2CO) Ammonia
(NH3) Hydrogen Cyanide (HCN)
Water (H2O) Silicon Monoxide (SiO)
Methanol (CH3OH)
15. Each maser produces radiation at a
characteristic frequency.
Because these sources are so strong, astrochemists use them to
find and identify new chemicals in space.
16. Masers reveal the characteristics
of their environment.
• They can be used as probes to
determine the density, temperature,
pressure, and velocity of a region of
space.
• Masers were used in the first proof of
the existence a black hole!
• Masers were found circling a massive
object. They circled very fast,
indicating that the object had to be
very dense. Mathematics showed that
an object so dense could not be
anything but a black hole.
17. Astrophysical Maser
• For an Astrophysical Maser to function in space, it requires a magnetic
field for the resonant frequency to be formed
• Can be used to identify conditions in space, such as temperature,
magnetic field, and velocity.
• OH, water, methanol- common types
18. Maser Applications
• Improved atomic clock
• Electronic amplifiers in radio telescopes
• Masers are also used as a low-noise radio frequency amplifiers in
satellite communication and radio astronomy
• Used as a non-lethal weapon (VMADS) for military purposes
19. Reconnaissance aircraft
• Reconnaissance aircraft are primarily used to gather
intelligence (collect information).
• They are equipped with photographic, infrared, radar,
and television sensors.
• Reconnaissance aircraft are normally the fastest aircraft
in the military, an example being the SR-71 Blackbird.
gran·ite (n)A very hard, granular, crystalline, intrusive igneous rock consisting mainly of quartz, mica, and feldspar and often used as a building...Used in similes and metaphors to refer to something very hard and impenetrable.
