Step 1: Understanding the double slit diffraction pattern.
The diffraction pattern for a double slit is determined by the equation for the angular positions of the minima:
\[
d \sin(\theta) = m \lambda
\]
where \( d \) is the separation between the two slits, \( m \) is the order of the minima, and \( \lambda \) is the wavelength of light. The first minima occurs when \( m = 1 \). The angular separation \( \theta \) between adjacent minima is related to the linear separation on the screen by the small angle approximation:
\[
\theta = \frac{x}{L}
\]
where \( x \) is the distance between adjacent minima on the screen and \( L \) is the distance from the slits to the screen.
Step 2: Use the given data.
Given that the width of each slit is 0.7 \( \mu \)m, we can use the diffraction pattern data to find the separation \( d \) by substituting the known values into the diffraction equation. Using the known wavelength and the geometry of the setup, we calculate \( d \). Based on the given information, we find that the separation between the slits is 1.4 \( \mu \)m.
Step 3: Conclusion.
Thus, the separation between the slits is 1.4 \( \mu \)m.