0x0A h e l l o _ w o r l d
But that limited the length of strings to 255 characters and using two bytes rather than one would add memory pressure. Dennis Ritchie then went with null terminated strings which has the advantage of allowing any size of strings and is consistent with the assembly they were used with. The drawbacks is decades of buffer overflows :)
Eventually I found an abstract on https://en.wikipedia.org/wiki/Null-terminated_string#History and there is a 2011 paper about it: Communications of the ACM - Volume 54 - Issue 901 - September 2011 - pp 42–44 - https://doi.org/10.1145/1995376.1995391 . Direct link to the PDF https://dl.acm.org/doi/pdf/10.1145/1995376.1995391