What is Work function: Definition and 86 Discussions
In solid-state physics, the work function (sometimes spelled workfunction) is the minimum thermodynamic work (i.e., energy) needed to remove an electron from a solid to a point in the vacuum immediately outside the solid surface. Here "immediately" means that the final electron position is far from the surface on the atomic scale, but still too close to the solid to be influenced by ambient electric fields in the vacuum.
The work function is not a characteristic of a bulk material, but rather a property of the surface of the material (depending on crystal face and contamination).
Background: self-studying. Very confused. Here are some initial questions I have about the photoelectric experiment. Some more may pop up later.
1. The book says we know photons exist due to energy considerations (such as emission or absorption). They also say that this photon energy is...
Hi everyone, I have to solve this homework without having any books where to find the theroical topic or examples, so if you could help me find materials that I can use to understand or you want to try help me understand how to get the solution would be very helpfull. I don't have enough time to...
1. a)I have plotted the graph on desmos and attached an image here.
b i. The threshold frequency is equal to the x-intercept ~ 5.6*10^14 Hz
ii. The work function is equal to the y-intercept ~ -3.75*10^19 J (would it be correct to state that this value is negative?)
c. Convert to eV;
3.75*10^19...
Question:
I have tried this and got work function to e 5.1eV
My concern is that for these type of questions, do I need to take into account the signs of some values; such as the negative sign for the charge of an electron? Or could I just take the magnitude for all the values
Any help...
I tried to apply the chain rule
$$X_{ik} = \frac {\partial U}{\partial \xi_{ik}} = \frac {\partial U}{\partial x_{i}} \frac {\partial x_i}{\partial \xi_{ik}} = \frac {\partial U}{\partial x_{i}} $$
and I got the force x-component of the force acting on ##P_i## I guess.
but I do not know what...
I have found different values depending where is read.
I should like have a graphene sheet on copper to be used in a ionizer to generate lots of electrons
The work function is the energy required to remove an electron from a solid to a point outside, it is a single value. Why is it called a function, instead of a single value? The word function suggests it is a function of some variable x.
Homework Statement
(Given a voltage against frequency graph)
Calculate the work function of Sodium and state any assumptions you have made.
My question is, what assumptions have I made?
Homework Equations
hf = work function
V = IR
The Attempt at a Solution
I know on a Voltage against...
I’ve been curious about understanding the mechanism behind themionic emission from what I have read I found that themionic emission happen when the energy from added temperature excess the work function of the material. I also readed when temperature excesses 1000k themionic emission happens but...
Since positive charge on the photocatode increases work function of electrons, does charging metal photocatode negatively decrease work function? If not, why?
Homework Statement
Photons with momentum p= 7.88 x 10-18 strike a photoelectric material which is in the configuration shown in the figure. The cutoff voltage is measured to be Vstop= 1.75 V. What is the work function of the photoelectric material?
Homework Equations
p = Ephoton / c
E0 = (c...
Is the reciprocal of the work function of ' Graphene ' a usable tool for the calculation of the electrical pressure * capacity or even an indicator of co-conductivity of a given area of (magnetically oriented) Graphene in relation to a substrate material which is also conductive ?
Dear Experts,
I am studying about a Stanford University innovation, using Molybdenum Disulphide and solar radiation to disinfect water at a very quick rate. I am unable to find details about photo sensitive properties of Molybdenum Disulphide. What is the work function of molybdenum...
Does the electric field strength required for field emission change with frequency? Better yet, at higher frequencies, is there a correlation with emission current?
Homework Statement
You need to design a photodetector that can respond to the entire range of visible light (400 nm - 700 nm). What is the maximum possible work function?
Homework Equations
E = hf = hc/lambda
The Attempt at a Solution
For 400nm, I got E = 3.11 eV
and for 700nm I got 1.78 eV...
Hello everyone! :)
I'm sorry that I'm posting something that might be obvious, but I'm still struggling to capture all the concepts behind the fundamental physics of this model.
Let's say, I have a 2D sheet of graphene, on which, there's a physisorbed layer of molecular dipoles (vdW bonding...
Homework Statement
Metal Surface is illuminated with 200nm wavelength light. Work Function of this metal is 3.0eV and its electric potential is 5V lower than a point of infinity.
Determine max K.E of photoelectrons, which are just emitted from the work surface.
Homework Equations
K.Emax= hf...
Could anyone help me with the following questions?
- Why is the work done by conservative forces equivalent to the potential energy?
- Why is the variation of the potential energy in such cases equals to the variation of the work function?
Thanks!
why does work function measured from fermi level
while work function is defined by lowest energy required to remove an electron from surface of materials
and fermi level the level have 50% chance to occupation that's mean there is level above it have electron inside so why we don't measure...
Homework Statement
I need to calculate the work function of a photoemissive material. Light is shone through a photocathode (cathode) and the stopping potential V, is measured between anode (stainless steel) and cathode using a picoammeter)
Following are the data measured/calculated
ν = 1.402...
Homework Statement
The work function for potassium is 2 eV. Consider light with wave length 3.6*10^-7 m hitting the potassium surface.
a) what is the stopping potential?
b) what is the kinetic energy and velocity of the fastest electrons emitted?
Homework Equations
KE_max = hf - Φ
q_e V_s =...
What exactly is the relation between these 3 quantities?
As far as I can tell the work function is the energy needed to bring an electron from the fermi level out into vacuum, while affinity is from the bottom of the conduction band.
Does this then mean that they can be used to calculate the...
The minimum energy required to eject an electron from the surface is called the photoelectric work function.To be precise to eject means force or throw (something) out
So energy equal to work function would surely eject an electron from metal surface
but according to the video below
At time...
Hi all,
I'm trying to understand work functions and am working through a paper but keep coming up with the wrong answer. Can anyone point out where I'm going wrong please...
Wavelength of light incident on surface = 560 nm
Max speed of ejected electrons = 1.67 x 105 ms-1
1 eV = 1.602 x...
Hi Folks,
I have been studying some scanning electron microscopy and read that the SEM tip is made from tungsten but is coated with a mono-layer of zirconium-oxide to reduce the work function from 4.5ev to 2.7ev, to make it easier to emit electrons (this is a field emission SEM).
Does anyone...
HI I am doing this equation : 14. When a certain metal is illuminated at 3.50x10^2nm the maximum kinetic energy of the ejected electrons is 1.20 eV. Calculate the work function of the metal.
I did this:
E=Ek+W
W=E+Ek
W=hc/Lambda -Ek
=(6.63E-34J.s)(3.00E8m/s)/3.50E2m)-1.20eV
=-1.2
That...
Homework Statement
The graph in fig shows the stopping potential as a function of the frequency of the incident light falling on the metal surface.
Find the photoelectric work function for this metal
Homework Equations
V_0 =\frac{hf}{e}-\frac{\phi}{e}
The Attempt at a Solution...
Dear all,
I learn that photoelectron spectroscopy can measure the work function of solid semiconductors.
However, some research papers reported it measured the ionization potential of solid semiconductor nanoparticle films.
As we know there's obvious difference between the work function and...
Hi guys, I'm constantly bothered by one assumption in my textbook..it says that the photon emitted by the accelerating electron boiled off from the cathode colliding into the anode, has E=hf neglecting the work function, since its negligible. I'm curious whether it's E=hf plus or minus the work...
Hi,
I posted this in the "General physics" section as I didn't see the Solid State part of this section.
I am quite confused here. So, I know that if you take any number of materials and place them in series the contact potentials subtract off so that the measured result is simply the...
If the energy of the photon is less than the work function of the metal, no photoelectric is observed.
I would like to ask if the photon would be absorbed even if its energy is less than the work function? or the photon would not be absorbed?
Homework Statement
In experiments on lithium, Millikan observed a maximum
kinetic energy of 0.550eV when electrons were ejected with 433.9nm light. When 253.5nm light was
used, he observed a maximum kinetic energy of 2.57eV. Using these results find
a) the work function for lithium, and...
Homework Statement
In a particular photocell, light with a frequency of 8×10^14Hz is directed onto the cell and it is found that a stopping potential of 1.2V is needed to reduce the photoelectric current to zero.
Calculate the work function of the metal in the cell.
Homework Equations...
Homework Statement
a) Write down the formula that relates the maximum electron energy, Emax. to the
frequency of the incident light in the photoelectric effect.
b) Calculate the maximum wavelength of light for which photoemission occurs for light
incident on a metal whose workfunction...
I'm looking at the ionization energy of some elements and their work function. To my astonishment these energies are quite different (factor close to 2).
How is that possible that if say a piece of copper has almost all its atoms in the fundamental state (room temperature ensures this I...
Calculating Work Function
I am having trouble identifying a metal (based on its work function) given the wavelength and stopping potential. I will give more specifics below but can anyone help me with useful formulas to make this a little more streamlined in the future? Thanks!
Ultraviolet...
Hello.
I am doing an electronics degree, and we were told in our solid state devices class that "work function is the energy required to release an electron from the influence of the material to vacuum. When the system is brought together to form the MOS capacitor, the Fermi levels must...
Homework Statement
I have experimentally determined the work function from the intercepts of a fit line in graph of stopping potential (J) versus frequency (Hz). This is from a photoelectric effect lab. The value of the intercept, which I believe is that of the work function, is returned as...
Homework Statement
In my attachment, the x intercept gives threshold frequency and the y intercept gives the work function.
Homework Equations
The Attempt at a Solution
Work function is the minimum energy needed to pull out an electron from the metal surface. My question is, from...
Work function of metals: http://hyperphysics.phy-astr.gsu.edu/hbase/tables/photoelec.html#c1
Copper work function - 4.7 eV
Silver work function - 4.73 eV
Silicon work function - 4.26 eV (http://environmentalchemistry.com/yogi/periodic/Ag.html)
The work functions of conductors are...
Why is it that the energy required to pull an electron out of a metal surface(work function) is approximately half of the energy required to pull an electron out of the free atom(ionization energy) of the same metal (or element)?
Is there any formula relating the two quantities?
Homework Statement
So today in class we did a lab where we calculated the stopping voltage of lights of different wavelengths. We did this experimentally. I have the wavelength, frequency, and stopping voltage of four different lights. I need to calculate the work function of the material, and...
alrighty, run into another problem in this assignment, while my last question i somewhat get... I am not sure at all what to do here, mainly cause i don't really get the graph...
Homework Statement
1. In a photoelectric experiment, the metal plate of an evacuated phototube is illuminated with...
Homework Statement
hypothetical one electron searsium element. n=-20eV, n2=-10eV, n3=-5eV, n4=-2eV. photon emission n3>n2 and n3>n1 will eject photoelectrons from unkown metal, but photon emitted from n4>n3 will not. what are the limits (max and min values) of work function of the metal...
What is work function of an insulating polymer (eg: Polystyrene ,PMMA etc..)? is it half of HOMO and LUMO? Do the ionization potential (IP) and Electron affinity (EA) change with work function?
IP= E(vacuum)-E(HOMO). So I guess this is always a constant. am I right?
But EA=E(Vacuum)-E(LUMO)...
Homework Statement
If electrons can be ejected from a silver surface using light with wavelengths as large as 262 nm. What is the work function for silver?
Homework Equations
work function=hf
c=f\lambda
The Attempt at a Solution
Given the wavelength, I solved for f =...
Homework Statement
The maximum kinetic energy of photoelectrons is 3.14 eV. When the wavelength of the light is increased by 50.0 %, the maximum energy decreases to 1.11 eV. What is the work function of the cathode?
Homework Equations
Kmax = E elec - E not
= hf - hfnot
hf =...