Midterm | (Lab) Latent Image Formation

Question 1

It has been known that crystals of (1) exhibit photosensitivity since the (2) (Carl Wilhelm Scheele;
1777).

Answer 1

1. silver halogens
2. late 18th century

Question 2

“It has been known that crystals of silver halogens exhibit photosensitivity since the late 18th century”

Answer 2

Carl Wilhelm Scheele;
1777)

Question 3

Examples of halogens

Answer 3

SILVER BROMIDE (commonly used)
Silver iodide
Silver Chloride

Question 4

Widely accepted explanation of formation of latent image in photography that metallic silver is formed at sensitivity centers located at imperfections in structure of silver halide crystals.

Answer 4

GURNEY-MOTT THEORY (1938)

Question 5

The GURNEY-MOTT THEORY (1938) is the widely accepted explanation of formation of (1) in photography that (2) is formed at (3) located at imperfections in structure of (4).

Answer 5

1. latent image
2. metallic silver
3. sensitivity centers
4. silver halide crystals

Question 6

10 Step Latent Image Formation

Answer 6

1: X-RAY PRODUCTION
2: POI
3: LUMINESCENCE
4: SECONDARY ELECTRON PRODUCTION
5: ELECTRON TRAPPING
6-7: INTERSTITIAL SILVER ATTRACTION
8-9: DISRUPTON OF CRYSTAL LATTICE
10: REOCCURENCE OF STEPS 4-9

Question 7

1: X-RAY PRODUCTION

Answer 7

-PRODUCTION OF PRIMARY BEAM

Question 8

2: PART OF INTEREST

Answer 8

EXIT BEAM INTERACTS WITH IR

Question 9

3: LUMINESCENCE

Answer 9

X-ray energies (Remnant Radiation) interacts with the IR, causing the outer shell electron of the phosphor material to become excited.

Eventually, the excited electron will return to its relaxed state, releasing HEAT in the form of visible light.

Question 10

4: SECONDARY ELECTRON PRODUCTION (4 steps)

Answer 10

1.Silver halide grains absorbs the light photons (From I.S).
2.Light Photons interacts with the Br- Ions resulting to IONIZATION.
3.This causes the release of secondary electron through Photoelectric effect or Compton effect.
4. Secondary electrons (photoelectron or Compton electron) wanders about the grain.

Question 11

5: ELECTRON TRAPPING (2 steps)

Answer 11

1.The wandering electron (Photoelectron or Compton electron) eventually gets trapped by the sensitivity speck.
2.This gives sensitivity speck a negative charge.

Question 12

Other term for INTERSTITIAL SILVER ATTRACTION/

Answer 12

Attraction of silver ion

Question 13

6-7: INTERSTITIAL SILVER ATTRACTION

Answer 13

The negatively charged sensitivity speck now attracts the positively charged silver ions.

Question 14

8-9: DISRUPTON OF CRYSTAL LATTICE (2 steps)

Answer 14

1.When attracted silver ion arrives at the sensitivity speck, its positive charge counteracts the negative charge of sensitivity speck. =NEUTRAL SENSITIVITY SPECK

2.This causes deposition of metallic silver at the silver halide grain.

Question 15

10: REOCCURENCE OF STEPS 4-9

Answer 15

Cycle reoccurs and more metallic silver is deposited at the crystal until LATENT IMAGE is formed.