Electron Spin Resonance Spectrometers Flashcards
1
Q
- Electron spin resonance involves detecting the detection of a physical phenomenon of _________ of
electromagnetic radiation.
a) Adsorption
b) Absorption
c) Radiation
d) Reflection
A
a) Adsorption
2
Q
- Electron spin resonance is also known as which of the following?
a) Electron paramagnetic resonance
b) Electron diamagnetic resonance
c) Electron paramagnetic reoccurrence
d) Electron diamagnetic reoccurrence
A
a) Electron paramagnetic resonance
3
Q
- When a strong magnetic field is applied to the unpaired spins of an electron, the electrons will be split into two groups.
a) True
b) False
A
a) True
3
Q
- The value of the magnetic moment is known as which of the following?
a) Thompson magneton
b) Bohr magneton
c) Goldstein magneton
d) Rutherford magneton
A
b) Bohr magneton
4
Q
- When the electrons are aligned either parallel or
antiparallel to the direction of the external magnetic field, the electrons will precess about the axis at a frequency that is proportional to which of the following?
a) Applied magnetic field
b) Electron magnetic moment
c) Applied magnetic field and electron magnetic moment
d) Neither applied magnetic field not electron magnetic moment
A
c) Applied magnetic field and electron magnetic moment
5
Q
- If the population of ground state exceeds the population of the excited state a net absorption of __________ radiation takes place.
a) Infrared
b) Ultraviolet
c) Microwave
d) X-ray
A
c) Microwave
6
Q
- If a weaker radiofrequency alternating magnetic field, having the frequency of precession of the electron is applied at right angles to fixed magnetic field, which of the
following occurs?
a) Fragmentation
b) Scattering
c) Resonance
d) Absorption
A
c) Resonance
6
Q
- ESR is remarkably sensitive when compared with NMR.
a) True
b) False
A
a) True
7
Q
- The population ratio can be given by which of the
following laws?
a) Bohr law
b) Beer-Lambert law
c) Kelvin law
d) Boltzmann law
A
d) Boltzmann law
7
Q
- The sensitivity of measurement is greatly enhanced by using which of the following?
a) High magnetic field
b) Low magnetic field
c) High electric field
d) Low electric field
A
a) High magnetic field
8
Q
- ESR sensitivity increases with __________ temperature and with _________ magnetic field strength.
a) Increasing, increasing
b) Increasing, decreasing
c) Decreasing, increasing
d) Decreasing, decreasing
A
c) Decreasing, increasing
9
Q
- Klystron can generate power in which of the following ranges?
a) 10 – 100 mW
b) 10 – 200 mW
c) 10 – 500 mW
d) 100 – 400 mW
A
c) 10 – 500 mW
9
Q
- Waveguides look like _________ cross-section pipes
with dimensions of the order of the wavelength to be
transmitted.
a) Triangular
b) Circular
c) Rectangular
d) Square
A
c) Rectangular
10
Q
- Reflex klystron is used in which of the following
frequency ranges?
a) 1000 to 2000 MHz
b) 1000 to 10000 MHz
c) 1000 to 15000 MHz
d) 1000 to 20000 MHz
A
d) 1000 to 20000 MHz
11
Q
- Under ideal conditions, a commercial X-band
spectrometer can detect of the order of which of the
following number of spins at room temperature?
a) 10^1
b) 10^5
c) 10^0
d) 10^12
A
d) 10^12
12
Q
- Microwave frequency can be tuned over a small range by adjusting the distance between which of the following?
a) Cathode and anode
b) Anode and the reflector
c) Cathode and the reflector
d) Cathode and grid
A
c) Cathode and the reflector
13
Q
- Microwaves are generated by __________ and the
power level is adjusted with the ________
a) Triode, rectifier
b) Pentode, attenuator
c) Klystron tube, attenuator
d) Diode, rectifier
A
c) Klystron tube, attenuator
14
Q
- Which of the following is also known as reflex oscillator?
a) Triode
b) Pentode
c) Special tube
d) Klystron tube
A
d) Klystron tube
15
Q
- Microwaves reflected back from the cavity are routed to which of the following?
a) Attenuator
b) Klystron
c) Load
d) Diode detector
A
d) Diode detector
15
Q
- Which of the following is adjusted as a fine control for frequency tuning?
a) Cathode
b) Anode
c) Reflector voltage
d) Grid
A
a) Small amplitude field modulation
16
Q
- In basic ESR spectrometer, the cavity length is
adjustable.
a) True
b) False
A
b) False
17
Q
- Which of the following routes are the microwaves
entering from the klystron towards the cavity?
a) Oscillator
b) Attenuator
d) Reflector
A
c) Circulator
17
Q
- By introducing which of the following, signal-to-noise ratio can be improved?
a) Small amplitude field modulation
b) Large amplitude field modulation
c) Small amplitude field attenuation
d) Large amplitude field attenuation
A
a) Small amplitude field modulation
18
Q
- The cavity resonant frequency should be equal to
which of the following?
a) Frequency of electric field
b) Klystron frequency
c) Frequency of magnetic field
d) Mechanical frequency
A
b) Klystron frequency
18
Q
- When klystron frequency is close to the cavity
resonant frequency, much less power is reflected from the cavity to the diode.
b) False
A
a) True
18
Q
- From which of the following are electrons emitted in the klystron tube?
a) Cathode
b) Anode
c) Grid
d) Reflector electrode
A
a) Cathode
19
Q
- Which of the following is the modulation amplitude
range of ESR spectrometer?
a) 1mG to 10G
b) 2mG to 15G
c) 3mG to 20G
d) 5mG to 40G
A
d) 5mG to 40G
19
Q
- Which of the following is the operating frequency of the ESR spectrometer?
a) 1.7 to 3.4 GHz
b) 1.5 to 4.2 GHz
c) 3.2 to 5.4 GHz
d) 8.8 to 9.6 GHz
A
d) 8.8 to 9.6 GHz
19
Q
- At which of the following frequencies is the magnetic field at the sample modulated?
a) 1 kHz
b) 10 kHz
c) 100 kHz
d) 1000 kHz
A
c) 100 kHz
20
Q
- The output of the klystron does not pass through
which of the following?
a) Isolator
b) Reflector
c) Power leveller
d) Directional coupler
A
b) Reflector
20
Q
- Which of the following is used as detector crystal in ESR
spectrometer?
a) Silicon rectifier
b) Silicon tungsten rectifier
c) Silicon boron rectifier
d) Silicon quartz rectifier
A
20
Q
- After detection, the resulting signal will have which of the following frequencies?
a) 1 kHz
b) 10 kHz
c) 100 kHz
d) 1000 kHz
A
b) 10 kHz
21
Q
- In which of the following ranges will the receiver time constant of the ESR spectrometer lie?
a) 0 to 10 s
b) 0.3 to 1 s
c) 0.03 to 10 s
d) 0.003 to 100 s
A
d) 0.003 to 100 s
22
Q
- Which of the following is the oscilloscope field width of the ESR spectrometer?
a) 0.2 to 40 G
b) 0.1 to 20 G
c) 0 to 10 G
d) 0.01 to 20 G
A
a) 0.2 to 40 G
23
Q
- Which of the following sensor is used in ESR
spectrometer?
a) Hall-effect sensor
b) Load cell
c) Strain gauge
d) Bourdon gauge
A
a) Hall-effect sensor
23
Q
- The magnet used in ESR spectrometer provides a
magnetic field which can be varied from ________ to
_______
a) 20 mgauss, 100mgauss
b) 200 mgauss, 20kgauss
c) 20 mgauss, 20kgauss
d) 100 mgauss, 10kgauss
A
b) 200 mgauss, 20kgauss
24
Q
- Klystron requires _______ for the klystron beam and
up to _____ for the klystron reflector.
a) +400 V, -730 V
b) +650 V, -400 V
c) +200 V,-530 V
d) +180 V,-270 V
A
b) +650 V, -400 V
24
Q
- What does AFC stand for?
a) Auto frequency correct
b) Automated frequency correct
c) Automatic frequency control
d) Automatic frequency circui
A
c) Automatic frequency control
24
Q
- Which of the following oscillator is used as 1230 Hz
oscillator?
a) Hartley oscillator
b) Crystal oscillator
c) RC oscillator
d) Wien bridge oscillator
A
d) Wien bridge oscillator
25
Q
- The klystron body is insulated from ground by an
insulating gas casket.
a) True
b) False
A
a) True
26
Q
- The 100 kHz oscillator acts as which of the following?
a) Transmitter
b) Receiver
c) Modulator
d) Transmitter and receiver
A
d) Transmitter and receiver
27
Q
- Which of the following removes residual harmonics
from the phase-detected signal?
a) High-pass filter
b) Low-pass filter
c) Band-pass filter
d) Chopper
A
b) Low-pass filter
28
Q
- The oscilloscope is used to display the klystron mode.
a) True
b) False
A
a) True
29
Q
- In the sample cell, which of the following is selected to give maximum optical transmission in the UV-visible region?
a) Tungsten
b) Quartz
c) Phosphor
d) Potassium
A
b) Quartz
