I was recently interviewed for a postdoctoral position at a top-three institution in the world. The PI has now offered me a position via email which does not include any form of contract. How do I ask politely for a proper offer letter/contract without sounding skeptical about the PI's email offer? I am an international student, and normally universities provide conditional offer letter to the international graduates contingent on the approval of the work permit by the government (which happens immediately after graduation). I will be graduating in May and would like to have a conditional offer letter signed to secure the position officially.
A top-three institution will certainly have experience with hiring international postdocs, and it is likely they have a standard process for doing so. In my opinion, you can ask your PI to advance the process without worrying about sounding skeptical. You might simply sound excited or eager instead. How about an email like:
Thank you for your kind offer. I am excited for the opportunity to work together.
If you have the time to send me an official offer letter or similar document, I can apply for the appropriate work permits immediately to prevent any delay in the start date. Is there any additional information I can provide that might be helpful?